Additionally any application using a GUI toolkit (like kde, qt or gtk etc) only needs to to update to a version that has native Wayland support. Which means most applications already support it. At least if they don’t use any X11 APIs directly (which is not that common).
Does that mean that every application will need to be updated to work with Wayland?
In theory yes. In practice most X11 applications can be ran using Xwayland as a compatibility layer
Additionally any application using a GUI toolkit (like kde, qt or gtk etc) only needs to to update to a version that has native Wayland support. Which means most applications already support it. At least if they don’t use any X11 APIs directly (which is not that common).
Yes, nominally, but there is a layer called XWayland to support backwards compatibility, so it’s not really a concern.