I haven't seen it in Wayland per se, but look at xpra. The way it implements remote app execution is in theory possible based on my understanding of wayland architecture. It doesn't have problems with detaching windows, etc. It currently requires a dummy X server, but it's not really in the actual display stack. It's a project that gives me hope for Wayland being able to provide a decent experience. Of course I don't know if Wayland is badly needed or not, but at least I could see a tolerable way of coping with applications that could not run over X without something like a dumb VNC session.