KDE Developers Continue Working Toward Wayland Support
As covered in several Phoronix articles to date already, many KDE Frameworks 5 / Qt 5 applications are already able to run on Wayland assuming they have no hard-coded X11 calls or other windowing system dependencies. However, for the Plasma shell itself and other key KDE components, there is still further work to be done for supporting KDE on the next-generation Linux display server without any X fallbacks.
As also expressed previously, ultimately KDE (and Wayland) developers in general are after programs getting to the point of being able to use the same binaries that will work under both X11 and Wayland so it comes down to abstracting the programs and APIs enough to switch at run-time between X11 and Wayland (or Mir) environments.
You can read about the KDE/Plasma plans for operating on Wayland via this mailing list post.