Well, it is a difficult question as linux is a bazaar-style ecosystem and while apple can change something fundamental at a whim, every significant change in linux will result in a split of the community (with different ratios) and the ‘winner’ will slowly swallow the other. But still then, noone has the incentive in open-source to start porting their app (and usually, since the new thing will be a smaller community at first, it creates a negative feedback loop) - fortunately those that depend on frameworks more often than not can simply be started in wayland mode and no change is required by the maintainer. For more special clients (like a screen reader) you will need more time as these programs require special handling by the compositor so one has to create an extension for that and a/some DE should implement it then. It will take some time and maybe some niche program that relied heavily on the X implementation will never be ported, or will have to be recreated with wayland in mind (I mean those scripting little programs that read what is under the cursor and the like)

Also, most DEs have really good backwards compatibility thanks to xwayland - because frankly some app will never be ported. (Also, accessibility is unfortunately quite the last thought on even paid platforms - and last I heard it was not all that great to begin with on linux)