I hope this thread can avoid being a beeching session about patch X2B.  This is a more strategic question than what happens in the next couple of months about a handful of irritating bugs.
 
A DAW is a platform, in the same sense that an operating system or web browser is a platform.  There is a life cycle that follows platforms.  In the early days, there are many competitors, each touting new ideas and different ways to do common tasks.  But over time, the best of those techniques and solutions find their way into ALL platforms, resulting in very little real difference.
 
With operating systems, they all do security, memory management, and have administrative tools.  And they all claim high performance.  It really is about the apps, not the OS.  OS suppliers still try to remain relevant by adding things like that tiled UI in Windows 8.  But there comes a point where that just isn't very interesting to customers.  And at that point, the second-tier platforms dry up and fade away.  How many operating systems have there been over the years?  For most people, today it boils down to 2: Windows and Linux/OS-X.
 
Likewise in web browsers.  Tell me in 25 words or less why my life would be transformed if I switched from Firefox to Chrome?  Firefox, Chrome, and IE are virtually identical, as far as I am concerned, and all the others (Opera, Mosaic, Netscape, et al) have disappeared or are well on their way.  It is not about the browsers.  It is about the websites.
 
DAWs as a platform are a little earlier in the maturity cycle yet, but it is obvious that there is convergence happening.  They all do loops.  They all do VST effects.  They all do bus routing.  They all combine MIDI, synths, and recorded audio.  Yes, there are still some significant differences, but it really is becoming more about the VSTs than the DAW itself.  That's why I chose SONAR.  X2 Producer gave me the best collection of great Synths and effects for the lowest cost.
 
So if you accept this premise, at least for sake of argument, it follows that the world will not need or want 15 DAWs that ultimately become practically identical.  And because this is complex software, the market will not provide enough income to keep 15 DAW suppliers in business.
 
So my question is, looking ahead (say) seven years, if the market has settled down to four survivors, which ones will they be and why?
 
 

Pro Tools
Cubase
That 'other' Mac DAW (whatever it's called)
SONAR
Maybe S1 and Reaper
 
JMO

as above, as well as FL.

The DAW's that will survive will be the one's that work best for our specific needs and with which the bugs we are willing to put up with. (none of em' are perfect)

Bitwig!!!!
 
naw, j/k.
 
The only DAW that I have my doubts about is Studio One.  I've toyed with the idea of selling mine (again), but it's practically worthless secondhand.  A few months ago, I put it up for sale on the KVR classifieds for $175 and got nothing but a couple of very lowball offers.  I've been watching the ads for it closely and nobody seems to be interested in it, unless the price is ridiculously low.  I'm guessing that most people have tried it thinking that the grass must be greener over there, only to find out that there's very little grass to be had with S1.

bapu
Pro Tools
Cubase
That 'other' Mac DAW (whatever it's called)
SONAR
Maybe S1 and Reaper

If I had to narrow it down to 4, my list would be a subset of yours:
ProTools, because they dominate among "professional studios" and that position will still be strong in 7 years because most people don't want to change what is working if their income depends on it.
 
Cubase, because that is owned by Yamaha, which has very deep pockets, and will see all sorts of secondary uses for the Steinberg technology.  But I also expect that Yamaha's influence will drag Cubase toward the trailing edge of the leaders
 
Reaper, because their price point gives them access to a much wider customer base.  It appears that is a business model that works and is only a small financial step up from Audacity.  I think that leaves very little room for anybody else at the bargain end of the spectrum.
 
I think those three are solid choices.  The question is who will be the 4th.  Limiting the list to 4 is arbitrary, of course.  Maybe there will be 5 survivors.  I don't believe there will be 7 solid, vibrant products in the market 7 years from now.
 
From what I have seen, SONAR should be that 4th product.  The technology is good.  There is a loyal customer base, although sometimes one wouldn't know that from this forum.  Roland is still a solid company, although they have probably given up a lot of their market power to companies like Zoom/Samson.  the SONAR user interface / work flow is good.  The quality of results is very good. Performance is outstanding.  They have good supplier relations, with virtually all VST suppliers providing support for SONAR.  I'm not sure any of the other DAWs have all these advantages.
 
And for those who think I am being too severe by suggesting that only 4 will thrive, look at the state of music notation software.  There have been dozens of products in the market over the years, and now it comes down to only 3 significant players: Finale, Sibelius, and MuseScore (open source).  That s the natural progression of platforms.
 
Finale  = ProTools
Sibelius = Cubase
MuscScore = Reaper
 
and there ain't no fourth player.

I can't answer this without seeing some sales numbers. Anyone know where I can find some?

I think they all share different wonders.  For example for a Music History School I would use Band in a box.  They introduce you to artists playing styles more or less.
 
I would study Reason for their Combinators because they actually have many setups based to specific instruments a Brass or a strings or an electric piano but with the compression set and the type of reverb so it gives you an idea about pre and post differences and how to judge quality and there are many of these set ups.  The other important thing is (in my Reason 4)  that it is not like owning a credit line for future purposes so what I have in it is pretty much what most people will be using unless they decide to purchase reason banks and things like that. 
 
RealBand and Protools and Reaper are buying a studio you get a mixer and a sequencer but not a lot of everything else and you aren't going to be exposed to setups so unless you have an idea of working flows you need to have an extra understanding before you try to use those. 
 
Cakewalk is buying a timeshare between well established studio's buying a music store full of gadgets and synths and effects.  Having access to a credit card VST DX VSTI but the draw back is you don't have the combinator examples so I for example study combinator settings and try to remanufacture them in Sonar to understand how to sensitize myself correctly.  Your perceptions only develop if you actually try this stuff. 
 
Also there is Orion Pro which is a lot like Reason except that while it gives you many instrumetnts and effects it doesn't have a combinator folder system so again you have to be aware of kinds of setups.  This is Cakewalks only weakspot.  Well Biab is a different idea.  I am glad I have all of these.
 
Cubase seems pretty similar to cakewalk X2 minus the synthesizer instruments.
 
Logic has a nice environment setup but how similar is the CAL script to the logic environment can you use Cal script on VST's  heck they need to put DR T's KCS level 2 on the back end.  Or is that really Ableton Live?  Which lets you use hotkeys in a playlist.  So Ableton is about access in a performance.    But I think you can see all of them demonstrate differences and really for what they are they are not that expensive so I over a ten year period got most of these. 

Hi Bliix,
that´s a good question,
but I remember several discussions on other forums about 
the sales numbers of music-sequencer- and afaik there never has been a chart for that!

methodman3000
I think they all share different wonders.  For example for a Music History School I would use Band in a box.  They introduce you to artists playing styles more or less.
 
<snip>
over a ten year period got most of these. 

What you are saying, I believe, is that you like the choice.  That's a different issue.  My thesis (which you are free to reject) is that platforms ALWAYS consolidate around a common set of functions, and in so doing eliminate the weaker competition.  I do not believe you will have that range of choice 7 years from now.  Hence, my question which products will still be alive at that point.