Is D&D in danger? D&D is in this weird place where it's in the middle of a lot of things. It's honestly pretty complex compared to actually rules light systems, but it's still much less complex than Pathfinder. If folks want more crunch they go to Pathfinder.

D&D has two pillars. Combat and everything else. I know that WotC defines it differently but generally I think it's easier to view like this. Everything I'm combat is extremely rigid. Everything outside is pretty flexible. Sure, exploration has more rigid rules than social interactions but I genuinely don't believe many people use rigid exploration rules. I think a lot of players dislike combat for a big variety of reasons. There are extremely few class-specific special things some classes can do outside of combat. Do fighters get anything special? Not really. And a lot of spells can totally negate specific things other players might be able to contribute.

It would be really nice to have flexible combat but I don't think there's a good way to do it without fundamentally changing the game. Instead, I believe every class needs to have meaningful ways to contribute to each pillar of play that cannot be one-upped by spells.

Another thing, I believe every class should have the same amount of limited resources more like 4th edition but I don't think there's a way to fix that in 5th edition or the new version without fundamentally rewriting everything.