The question whether MIDI should be dropped is... curious, to say the least.
 
The simple facts of the matter right now is that you pretty much can't do contemporary music production without it. Whether you're using virtual instruments, control surfaces or hardware automation, you're pretty much bound to be using MIDI for it. Any DAW that aspires towards professional use simply has to have it.
 
Now, I appreciate that these days MIDI looks more than a bit clunky and dated - mostly because of its limited resolution. Nevertheless, it's the only thing pretty much everyone is guaranteed to understand, so it's what we gotta work with.
 

Thedoccal
Midi won't work for online collaboration.  Audio only.
But midi works for creating what will end up being that collaborative audio file.
So midi will stay...at least in the Sonar version that Bandlab adopts for it's platform.

I don't mean to sound like I'm picking on you, Thedoccal, but that's not even wrong. MIDI is not only perfectly suited to online collaboration, but it facilitates certain things that you simply wouldn't be able to do otherwise. MIDI allows us to separate the composition/performance data from the actual sounds and that means the composer or performer does not have to have the best possible sound generators on hand or be proficient in getting superior audio.
 
To give an example: currently I have a couple of projects going where I get the MIDI data, transform it to suit my choice of instruments (this applies to drums especially, but I also do stuff like chart generation in order to record live guitar parts etc.) and work from there. Were I to be forced to use audio only, the results would either be inferior (being stuck with a cake I can't unbake) or I'd have a lot more work on my hands (needing to pick apart the parts I want to reprogram or re-record by ear).
 
Frankly, I can think of very few collaborative scenarios where MIDI is present and I would not want to use it. The ability to get inside the performance and to swap out tone generators for what works best in the mix is just too valuable. Even if my collaborator can provide me with excellent renders that would be used in their audio form, I still might want the MIDI data for additional layering and such.
 
The only reason I could see for dropping MIDI support is if a better global standard comes along.

I think of MIDI as the 'machine language' of music.  It allows you to see a performance in the way it was actually performed, note on, by note off.  Much easier to edit and move an event around than to edit audio. 
 
There was a time before all of the current audio time and pitch shifting and stretching algorithm magic was possible.  So you can do more with audio now than ever before, but you still cannot completely unbake a cake.
 
I like to be able to see music in notation view and piano roll view side by side.  I think that composers and arrangers would view MIDI as a data transmission mechanism to their 'electronic' musicians.  Write a score in a music notation program, and then export it as a MIDI file to be played back and/or edited in a DAW.

Re: Midi - should it go or should it stay ?

 
Why do you or why would you have you choose? 
 
Is there a reason why you seem a need to choose??

Last year I produced a Children's CD professionally.  I worked with a married couple.  She did all the singing but he created all the midi arrangements, played guitar very well and keys for the purposes of playing data in.  We worked apart for a while using midi and the standard set of GM sounds.  Sending midi files to me once the basics of the arrangement were fleshed out.  I saw (e.g. PRV view)  and heard exactly what he was hearing which was good.  We both used a Roland Canvas as the playback machine.  The choice of presets was excellent in that it conveyed a lot about the types of sounds they were after. 
 
Midi allows extensive sound shaping and backdrops to be created and changed incredibly easily and this includes tempo alterations.  To me it is not clunky nor dated.  I think midi was invented very well to start with as it has lasted so long, it has stood the test of time, has been running excellently for decades and does not seem to be going anywhere.  They built tons of (unknown) future use into it from day one.  It is a fine example of this to be precise.  It seems to run seamlessly alongside my current DAW.  They are looking at new improved midi protocols now which is only going to get even more interesting. 
 
A midi note one only takes 1mS of latency to send.  That is super fast, even in terms with today's audio latencies.  If you only put one synth making one sound on one midi port then you are in for some pretty tight timing.  The internal resolution of programs like Studio One handle very well the capture and playback of subtle midi performances.
 
For the CD, by the time they came around to record all the vocals and guitar parts, I had all the sounds reset to high quality patches.  Some of his midi data had to re worked and improved, I added extra stuff.  We took some stuff out etc.. It was a very productive way to work.   I have not done a lot of CD's involving midi collaboration prep, but I was very pleasantly surprised at how well the use of the GM standard allowed us to do enormous amounts of work before studio sessions took place.  Everyone was super prepared.
 
A large and powerful hardware synth setup allows you to leave a lot of midi parts as midi files playing the instruments live each time you hit play on your DAW.  You need a synth mixer to do this properly.  Sounds can be changed and this is one powerful feature.  No CPU resources being used now for the purposes of making sounds. This eases the load on your computer enormously.  Of course now your virtual instruments can be added in  (you wont need as many) adding complexity and excitement to the arrangement.  Right near the end you turn everything midi into audio and then can carry on working with the music in that form.  More effects, more editing, more everything.  If you are not happy with certain parts, you can turn the midi parts back on at any time and get one or more synth parts playing live again.  Then change the part. 

Why is everyone rushing in to defend MIDI as if there is any universe where MIDI would be removed or omitted from any DAW?

IIRC the OP stated in a later post that he meant the continuous development of MIDI, not whether or not it should be removed.
I agree that MIDI is here to stay, and is more and more relevant due to the quality of instruments available these days.
 

My opinion is that the last version of the MIDI editor in Sonar Platinum became harder to use than the way it was before. At least in the way that you were able to view tracks, and how you picked which ones you wanted to see. I saw a few complaints about this online after it was changed. Wasn't a show stopper though as you could still edit your midi tracks. Hopefully that came out right...
 
After Gibson announced it was killing off Cakewalk, I invested in Pro Tools and a lot of education to make sure I could use it to its fullest. I found that PT has excellent Midi editing features but is no where near as stable as Sonar on the PC platform. Again, my opinion is that midi editing in PT is actually better and easier to do than in Sonar. That's about the only feature that I can honestly say I use constantly where PT beats Sonar. Sonar wins at just about everything else, including it's Midi event list and how you can edit that. I don't want to sound like I'm knocking PT. It's a great program, but Sonar Platinum is much nicer to use - not to mention that its interface looks so much better.
 
As long as I don't have to sink a chunk of money into a new Bandlab/Cakewalk/Whatever It Will Be Called product, I will gladly switch back from Pro Tools. You can do some amazing things with Pro Tools, but same with Sonar Platinum and you didn't have to fight with the issues PT has on the PC platform. I think that's where cakewalk missed a marketing opportunity. It is as feature rich as PT, but no where near as buggy. Plus, Cakewalk support was a lot faster too.

wdaweb
My opinion is that the last version of the MIDI editor in Sonar Platinum became harder to use than the way it was before. At least in the way that you were able to view tracks, and how you picked which ones you wanted to see. I saw a few complaints about this online after it was changed. Wasn't a show stopper though as you could still edit your midi tracks. Hopefully that came out right...
 
After Gibson announced it was killing off Cakewalk, I invested in Pro Tools and a lot of education to make sure I could use it to its fullest. I found that PT has excellent Midi editing features but is no where near as stable as Sonar on the PC platform. Again, my opinion is that midi editing in PT is actually better and easier to do than in Sonar. That's about the only feature that I can honestly say I use constantly where PT beats Sonar. Sonar wins at just about everything else, including it's Midi event list and how you can edit that. I don't want to sound like I'm knocking PT. It's a great program, but Sonar Platinum is much nicer to use - not to mention that its interface looks so much better.
 
As long as I don't have to sink a chunk of money into a new Bandlab/Cakewalk/Whatever It Will Be Called product, I will gladly switch back from Pro Tools. You can do some amazing things with Pro Tools, but same with Sonar Platinum and you didn't have to fight with the issues PT has on the PC platform. I think that's where cakewalk missed a marketing opportunity. It is as feature rich as PT, but no where near as buggy. Plus, Cakewalk support was a lot faster too.

Ummmm What??????????????

Interesting reading Steev's mention of the Kawai K11.  I have a Kawai K5000W which is the much later and the most powerful version of this synth.  It has both Additive and PCM based engines.  Two midi ins and two stereo outs too. Can be treated as two separate synths in one. Not many can do this.
 
The Additive side sounds amazing.  I have found many patches for it on line, probably all of them.  They are wonderful.  Not too much bottom end wither.  Many Kawai layers can be had with little build up in the low end.  The K5000 can do 6 layers per note and there are 6 effects processors too.  I have a Doepfer Pocket Dial which has 16 endless knobs on it controlling the 16 most important parameters of an additive sound.  So editing is active all the time.  
 
The PCM side is very good too loaded up with a huge sample base.  689 waveforms.  It sounds way different to the additive side.  Quite earthy and organic at times. It layers well with the additive sounds too.  There is also a built in GM sound engine with its waveforms and patches. K500W also features sequencing options. 
 
The white keys are longer than normal and have proper lead weights under mine.  The action is real nice and it is very good to play.   Most of all it has a range of sounds including lush and detailed and complex too.  It works well with the mod wheel and after touch.  It is one beautiful instrument.
 
I also have a Roland JD800 and it is completely different but also quite stunning.  That and the Kawai dance together rather beautifully. The JD can be super analog at times but super digital at other times.  It is like having two synths in one as well. Between the two of them I can get 4 distinct textures.
 
 

Keep and update MIDI capability.
 
The next generation of MIDI is arriving NOW!  New specifications were released at 2018 NAMM.  The next generation is called MIDI-CI and is an addition to the original MIDI 1.0 specification.  That means anything based on MIDI-CI will be backward compatible with MIDI 1.0.  You can read more about MIDI-CI here:  https://www.midi.org/articles/midi-manufacturers-association-mma-adopts-midi-capability-inquiry-midi-ci-specification.
 
MIDI has adapted well to more than thirty years of computer evolution.  A computer built in 2018 using either the latest version of Mac or Windows can still communicate and control a MIDI keyboard or sound module built back in 1983 when MIDI was born.  MIDI has adapted to moving from transmission over dual, five wire cables to USB, Bluetooth and wi-fi.  MIDI is how most DAWs communicate with VSTs.
 
Follow the link above and read how MIDI is adapting.  The DAW that wins the MIDI battle is going to be the DAW that is able to fully utilize existing and upcoming MIDI capabilities.  Bitwing, Studio One, Ableton and Reaper demonstrated compatibility with the new standards at NAMM.  The tools presently available in Sonar are, for the most part, seriously overlooked and neglected.
 
I'd start with the MIDI effects GUIs.  Update the GUIs to reflect whatever new look the new DAW has.