At the most optimistic, Wayland is still one or two years away from mainstream use. Even then, most apps will run under the rootless X server.
X will finally disappear if and when all apps upgrade to GTK3 or QT5 (which might be never).
Wayland is X designed properly, however it is basically the same thing. It does not seem to yet acknowledge the wider changing context within which desktop Linux has to operate, i.e. we are moving away from a world where manufacturers produce devices for Windows (and don't care about desktop Linux) into a world where manufacturers produce devices for Android (and still don't care about desktop Linux).
Canonical became flame-bait central over Mir and their reactive 'community engagement' (troll feeding), but I wonder if they have a point, that by the time Wayland is widely deployable it will be outdated?