Well the work done to prep for moving to Wayland has probably helped a lot for moving to any other not-X, I would imagine. E.g. Qt has a lot better abstraction capabilities now than it did for Qt 3.
I'm well aware of where Qt has (and has not) been able to run.
What I'm saying is that it's a lot easier to make new ports now than it was back then. This was mostly driven by Nokia's requirements, but it's still useful in the context of making a version that would run on Mir.