rasterman, EFL's main dev, has already said they are supporting and backing Wayland and that Mir is just politics. That pretty heavily implies that they arent gonna support Mir in mainline.
That leave Qt, and KDE. Martin has already said no distro-specific patches will be accepted in Kwin, and right now the only one using or going to be using Mir is Ubuntu so support of Mir in Kwin is out of the window unless other distros pick up Mir (That ARENT ubuntu based -.-)
Digia may be swayed to support Mir just for commercial reasons, and if so, awesome, good for Mir. But Ubuntu is still gonna have to support out of tree patches for EFL, GTK and KDElibs