XFCE is still using GTK+ 2 as far as I know, which is deprecated. Since GTK+ 3 is... well, a pile of manure to put it bluntly, are there any plans to move it to Qt 5 and maybe support Wayland on the way? That's something I'd really like to see, as XFCE is my favorite DE and I'd really like to use Wayland.
Seems like I read that if Wayland were going to be supported, it'd be some time down the road (years, IIRC).
It would have been here that I would have read about it; try doing a search for the term.