Any progress on that?
@marmistrz: Did you document your approach anywhere, so that someone willing to play with this does not have to start from scratch?

Did anyone consider building a Qt5 compatibility layer for Qt4? If you try to port software that doesn't use (m)any of Qt5's new features, it's actually just renaming some classes and reimplementing a few Qml properties. This task is quite similar for many applications and such a layer could save a lot of time if done only once.