The other possibility - I just saw an article on phoronix noting the adoption of the Android window server layer (SurfaceFlinger or something like that) on ubuntu mobile. Not familiar at all with android underpinnings, but would that be another alternative to Mir? i.e. more modern window server, actively developed by Google dollars, etc?
SurfaceFlinger is missing a lot of essential desktop display protocol components, like native windowing, chrome allocation, it only uses openGL ES, and isn't environment agnostic at all.
Also, completely opinionated, but after reading some of the SF code in the AOSP, it seems like just as much of a mess as X is implementation wise. It is all over the place.
