I've been blindsided by this. I've been a user since Pro Audio 8. The amount of time and money I've sunk into the platform is one thing. The abruptness and timing of the shutdown has been even worse. I've been working on an album, almost complete, all in Sonar, and I'm going to have to move to another DAW. I may even move from Windows to Mac.
 
So I've been trying out every option. I already had Pro Tools, but never used it as primary. On the positive side, it has the most rock solid audio engine and low latency of any DAW. On the negative side, its interface is very non-intuitive, and it has bare bones tools for creation. It's not made for musicians or producers. It's made for engineers and studios. Studio One is very promising, but it also is clearly not as polished and mature as other platforms. It had trouble detecting my interface settings, and virtual instruments that work on other platforms showed up as unauthorized. I had to run it with higher buffers than Sonar or Pro Tools (the lowest) to avoid stuttering. I like the interface, and I hate losing ARA with Melodyne. But I'm concerned about moving to a less mature platform after this experience with Sonar. I don't want to go to something that's going to evaporate again. I've tried to install Cubase Elements, but I can't even get it to launch...so that will have to wait. Which leaves the possibility of getting a Mac and going to Logic. I'm tempted, because it is stable, and has a very large user base and long history. 
 
I know everybody has biases on this subject, but I wouldn't mind objective opinions about other platforms. One thing that trying others has shown me is how good Sonar is/was. It had continuously improved over time, and was in a very good place. it looked like they were continuing to innovate and move forward. And then suddenly, they're shut down. This is brutal.

I would give Reaper a closer look. People have this strange idea that because it isn't expensive and doesn't come with 500gb of bundled bloatware it can't be a serious contender. Nothing could be further from the truth. I spent some time with a few things including Mixcraft, Mixbus, Samplitude and Studio One, and I already have Live and Reason, and I have to say it was Reaper that started getting me excited. It's staggeringly deep, incredibly fast and stable and efficient, starts up in about 3 seconds - literally - on my 10-year-old machine, and has a thriving and helpful community, who have contributed not only hundreds of skins (a number of which look superb) but also many hundreds of add-on scripts, plugins, macros and such to extend the program's functionality even further.

I may sound like a fanboy but I'm very much not, I'm just very very impressed with what Reaper can do, how clean and bug-free it seems to be, and how intelligently it's been developed. And I like the business model - no copy protection at all, no marketing at all other than word of mouth, a fair and reasonable pricing system, and above all fast, continuous, responsive development. There's an infamous thread where someone suggested an idea for a way to achieve VCA fader control (before it was fully developed as a core feature), and Justin had a working version up and running in 25 minutes. Think about that.

The workflow is different than Sonar to be sure, but that said it's also very flexible, you can use it in a number of ways, and it does 97% of what anyone is likely to have been doing in Sonar out of the box, plus a whole lot that Sonar can't do (check out the subprojects feature and ponder the possibilities for a while), and when you add scripting and macros from the community (or roll your own) it's an absolute beast. I'm really surprised more people aren't migrating there. For me it was no contest once I realized what a heavy hitter it's become, and that without becoming bloated and buggy in the process.

subtlearts
I would give Reaper a closer look. People have this strange idea that because it isn't expensive and doesn't come with 500gb of bundled bloatware it can't be a serious contender. Nothing could be further from the truth. I spent some time with a few things including Mixcraft, Mixbus, Samplitude and Studio One, and I already have Live and Reason, and I have to say it was Reaper that started getting me excited. It's staggeringly deep, incredibly fast and stable and efficient, starts up in about 3 seconds - literally - on my 10-year-old machine, and has a thriving and helpful community, who have contributed not only hundreds of skins (a number of which look superb) but also many hundreds of add-on scripts, plugins, macros and such to extend the program's functionality even further.

I may sound like a fanboy but I'm very much not, I'm just very very impressed with what Reaper can do, how clean and bug-free it seems to be, and how intelligently it's been developed. And I like the business model - no copy protection at all, no marketing at all other than word of mouth, a fair and reasonable pricing system, and above all fast, continuous, responsive development. There's an infamous thread where someone suggested an idea for a way to achieve VCA fader control (before it was fully developed as a core feature), and Justin had a working version up and running in 25 minutes. Think about that.

The workflow is different than Sonar to be sure, but that said it's also very flexible, you can use it in a number of ways, and it does 97% of what anyone is likely to have been doing in Sonar out of the box, plus a whole lot that Sonar can't do (check out the subprojects feature and ponder the possibilities for a while), and when you add scripting and macros from the community (or roll your own) it's an absolute beast. I'm really surprised more people aren't migrating there. For me it was no contest once I realized what a heavy hitter it's become, and that without becoming bloated and buggy in the process.

+1 I think that for all the same reasons, I'm moving over to Reaper. For those who agree that it's not nearly as visually impressive/stunning as Sonar (yes, we've been terribly spoiled by such an attractive interface) take heart in the fact that you can easily skin Reaper with options out there that's meant to look like nearly anything! Check out the Imperial theme by White Tie, or Imperial Dark Side.

Agreed - those are lovely, and so are Abbey Road and a few other hardware-inspired ones. But after a few days poking around Studio One - which I really liked, to be fair, just not quite as much as I ended up liking Reaper - I found myself drawn to a clean, modern look more than a retrogroovy hardware one - at least for daily work - so my favourite theme at the moment is Hydra. But of course since applying a new theme is basically instantaneous, I can dial up something else whenever the mood strikes!

aahladas
I know everybody has biases on this subject, but I wouldn't mind objective opinions about other platforms. One thing that trying others has shown me is how good Sonar is/was. It had continuously improved over time ...

I do totally agree to that, but in respect of objective opinions it would be helpful if people would add why they think a particular DAW is preferred. Because as you write "everybody has biases".
 
After testing some other DAWs that is also my conclusion "how good Sonar is/was". I was doing an evaluation some years ago, before I purchased Sonar X3 (now Platinum LT). Back then I was clearly drawn to Sonar and even today I have the same opinion.
 
For me the main purpose of a DAW are: Recording (only 1 track at a time) vocals, guitars and bass, vocal comping, intensive use of Melodyne for adjustments, recording VST instruments (I am doing a little MIDI in the DAW, but I enter most of my MIDI data in my own programs), mixing and a base mastering. In my workflow I do those things above in minimum 3 projects per song, i.e. I record do comping/Melodyne and then export the results as single audio tracks (also the VSTi tracks). This is also a good way for backup purpose. Then I create a new project for mixing with those audio files and in the end I create another project for mastering.
 
Up till now I have tested Studio One, Live, Cubase, Samplitude Pro, Tracktion and Reaper and for my taste only Samplitude Pro and Reaper are left in evaluation.
 

I'm leaning towards Logic at this point, because my computer has been getting old anyway, and once you have a Mac, Logic is only $199. It's got some of that Apple simplicity in the interface (GarageBand is basically a simplified version of it), which is not all bad when you want to create and not worry about the tools. And I already have a ProTools subscription, so I can keep using that as a compliment - or anything else, since Sonar was the only major Windows-only DAW. Considering how many hit records are being produced with it, Logic has to be good enough. And I can mix in ProTools if I need it. That is what's usually happening in the "big leagues" right now (although Ableton and FL Studio are being used a lot for EDM and Hip Hop, respectively). I'm not interested in being a guinea pig for an underdog at this point. I need everything to work without issues. 
 
Studio One is looking good, but it's not perfect, and I don't want anything that has a chance of being discontinued because of company mismanagement. Not that Presonus will, but Apple and Avid seem like safer bets. I've messed around with Reaper before, and it's not for me.
 
Still can't believe that after almost 30 years, Cakewalk just evaporated in the blink of an eye. I was worried when they were sold to Roland, and then Gibson, but they looked like they were still holding together, and on an upswing. The software was never better. I don't ever want this to happen again to my main platform.

My unbiased opinion is all the other DAW's are different. Saying they are better or worse would be a biased opinion. Just like I always say with audio interfaces. Everybody will recommend the one they have chosen but that doesn't mean it's the right one for you.
You are the only person who can choose.
Myself I will stay with Sonar. I will be able to use it for a long time yet. It is just fine the way it is even with it's few minor bugs. As we all found out by trying a few other DAW's, Sonar is a great DAW and the grass is not greener for all of us on the other side of the fence. I happy for those who have found something better. 
 
I also have a few other DAW's as I always have, but its more or less a waist of my time getting up to speed with them because I will stay with Sonar. 
 
If you havn't already you need to do some reading in the Software forum where there are dozens of very long threads compairing all the other DAW's. You'll certainloy find what you want and even draw some conclusions if you have the 6-12 hours to read it all. 

Just to be clear... All of my software is up/running and activated (I used command center).   Am I correct in assuming as long as it's activated already, I'm all set as long as I don't uninstall or try to move to another PC?  In other words it will continue to work on my studio PC as long as my studio PC remains my Studio PC ?  
 

mileskb
Just to be clear... All of my software is up/running and activated (I used command center).   Am I correct in assuming as long as it's activated already, I'm all set as long as I don't uninstall or try to move to another PC?  In other words it will continue to work on my studio PC as long as my studio PC remains my Studio PC ?  

Well that's the key question, and the answer is there isn't really an ironclad answer. For the present and immediately foreseeable future, the answer is 'yes, but...' - and it's a big but. Basically (and there are many threads here discussing it, and others likely more qualified than me to speculate) everything should be cool for a while anyway, but there is always a chance that Microsoft will make a change to Windows at some point that will break something crucial in terms of Sonar's ability to install or function. I don't know what OS you're on, or if you are in a position to cut your studio PC off from the internet or freeze it from updates, but while those are one avenue that some here have talked about, it doesn't strike me as a perfect solution for anything other than the immediate future.
 
Now, the dev team at Cakewalk worked pretty hard to future-proof Sonar as much as possible with regards to core Windows interactivity, and were in contact to at least some degree with people at MS working on things like the audio stack, so there's a good chance nothing will bring the program to its knees next week or next month or maybe even for the next year or couple of years. People have noted that earlier versions of Sonar, and many other programs, still install and work very nicely in the most recent Windows builds. And Craig has even speculated that quite possibly, since it was built to play nice with some of the emerging technologies at the OS level, performance might even *improve* for a little while as these technologies improve and mature. Someone else also pointed out that while no further development means no new features and no bug fixes, it also means no new bugs, so if everything you use is working for you now you can relax about it getting messed up in a future update.
 
But it doesn't take a rocket surgeon to grock that there's a limit to this and at some point Sonar will be left behind, which is why many of us are exploring options for a future mainstay DAW that is still in active development.  
 
 

For those who move toward Reaper.... keep your projects in CWP and till you actively used ProChannel modules (other then EQ), do not rush with exporting everything. A simper way to move projects is under investigation (by me)
 
Sonar X3 on offline PC without any updates can work virtually forever. How long Sonar 2015+ will work in such conditions is unclear, there are known precedents  that activation can "expire". CW has promised to release offline activation in case the authorization servers are intentionally stopped. I guess for the near future (2018) everything is safe. But then everything can happened. Even without intention, authorization services can be interrupted (hacks,  hardware/software failures, etc.). So there must be someone who can fix such problems and there is no information for how long and till which degree Gibson is going to pay for "afterlife".