2E wasn't as much of a mistake, so much as 1E was: AD&D was all a mistake. Moldvay/Holmes should have been the only D&D product, splitting the game was insane.
However, History seems to have largely proven that approach was a mistake: we know that 2024 has already outsold the lifetime sales of the 3E, 3.5, and 4E rulebooks. "Needing" a new publishing to revive sales and refresh stuff that is dated (Race to Species, new art aimed at current styles...
What recent third party additions are unusable on Beyond...? WotC seems to have taken MCDM, KP, and other 3rd party stuff from 5.1 and just put it up as-is for mixing and matching with new stuff.
Maybe: I think more time makes further changes even less and less likely. There is no ROI reason for WotC to make those changes: future fans won't care, and itnwould tick off people who had been playing for at that point theoretically decades. I'm sticking to 2024 being the most radical...
I would say that would make any such change even less likely: if after 10 years, backwards compatibility was a primary goal...after 20 years, 30 years...that will only increase.
Yeah, it doesn't make much sense: Call of Cthulu has been doing exactly this sort of stable approach for over 40 years, and is arguably the most successful RPG after D&D and it's clones.
But that is basically how they operated the surveys: sparks joy or doesn't spark joy. And ultimately that led to what I would consider a stronger move forward.