The most likely outcome is the Canonical toils away themselves on Mir, and everyone else works on Wayland/Weston. Maybe at some point Canonical decides that it's better to just use Wayland, but that's about it.

Wayland is already at 1.0, and has support from Valve, Nvidia, and AMD behind it. I don't see it disappearing soon. Especially since the implementation of Mir isn't even usable yet (while Wayland is).