Once the desktops switch to Wayland and all distros ship with Wayland by default, support should slow.
Ideally, developers stop improving xwayland over time and go into maintenance mode for a bit. Once it goes into maintenance mode, developers should naturally fall off as it winds down.
If every desktop makes a very public announcement about the xwayland protocol being put into maintenance mode, actively supported apps should switch over. It’s up to the public how long they want to keep maintaining xwayland (open source etc).