I think it's a Ctrl+T scenario, once users get used to the new way they don't use the old anymore, but each one to his own time, they can't be pushed if not ready.
I remember suggesting a multipicker years n years n years ago then Rusty also suggested this, this is a good step.

I keep an old exe of different versions for support.
Look at the new Tracks view, so many didn't want it to become a "DAW" but with all those Util tracks and the Track window that horse has bolted, it's a great improvement appreciated by so many users. The thing is you can still just use Audio Edit and the Piano Roll and hide the extra UTil tracks and Tracks window.

Things have to move ahead, look at the BiabVST now in Reaper, instantaneous !! I had to show that working for ages with so much code, pics and videos with like near zero interest or support from most maybe due to not understanding ??? and saying that most users have old computers with old hardware so Biab has to be limited and can not progress because of this, but you can see plainly now it working in action in the BiabVST (there is still more to do like playing the track data direct in the BiabVST (so other DAWs can enjoy the speed) and have all the code in the VST that I will most likely have to now do also to show that working frown as there still seems to be some resistance to that. ), you can see Riff Edit now in the Tracks window giving way more control the same as I showed in Reaper with the RT/RD sections.
So much of this stuff that is now implemented I showed years n years n years ago, so it is still way behind of where it could of been by now smile

https://stash.reaper.fm/u/ReaTrak (Scripts for Biab Reaper)
Open SGU in Reaper Instantly