BlackBerry, Canonical, and Jolla came to exactly the same conclusion which is why all these use Qt these days in their mobile offerings and not GTK/Hildon. Even Samsung and Intel support Qt next to EFL in Tizen but not GTK/Hildon.
GTK as it exists now is dying. Even the GTK maintainers know that which is way even shortly after GTK 3.0 came out they thought about how to fix GTK and make a 4.0 release happen. As reported recently on Phoronix they plan to replace large parts with Clutter.