KDE is moving towards Wayland, but is currently still way behind X11, around Alpha quality last time I tried (i.e. it can even crash right away after the desktop shows, of course this will vary from one device to another). One guarantee, though: no further development on X11 backend, everything will be focused on Wayland.
With regard to Nvidia, please keep your expectations low. If Wayland alone with graphics card whose driver is directly committed by the vendor (e.g. Intel) to the kernel tree is not yet stable, let alone an out of tree proprietary driver from Nvidia.