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Replacing X with something new would be very welcomed by me. I'm a GUI toolkit and desktop application developer. X has the worst performance of the big three (OSX, Windows, X) - even a relatively new project like Haiku seems to have better graphics performance than X.
I hope one of the big players like IBM could start such a project. Many individual developers have tried, but those projects very quickly get discarded.
As for the "wonderful" remote/networking support built into X - I don't see that as relevant any more. That was designed for mono terminal displays of 20+ year ago. VNC, RDP and a host of others all manage the same thing (in color) with much better performance!
Apple had the right idea with OSX, by writing their own GUI - it's time the rest of the *nix world wakes up to that fact - X11 sucks in performance.
I run Linux at work and home, as my only development platform. Windows only lives in VM session on my systems. So please don't take this up as a rant/flamewar request - it's purely my observation of X in my day-to-day work. Edited 2010-06-26 09:12 UTC