Phoronix: Drafting Plans For X12, The X11 Successor

While it's likely in the next two to three years that the Wayland Display Server will play a pivotal role on the Linux desktop, the X11 Server isn't going away immediately. There's still legacy X applications that must run, uncertainty about what Solaris/BSD will do for their display server due to their graphics driver shortcomings, and other uncharted issues. It's possible that X12, an improved version of the X11 protocol, could even be developed...

http://www.phoronix.com/vr.php?view=MTAwMTc