Do you think Xorg should be rewritten from scratch?
Many things looks temporary in xorg: the memory manager, the 3d driver model, the 2d acceleration method, video playback...
Years are passing and things seem to point nowhere, everybody continue to say "hey, new and better acceleration, wow!" but after 2 mins people start complainting about their new ITA/DMA 4950+1 or PerFidia GeoStrenght 9900&1/2 or OutTel 995GMX performing as a SVGA from late '80s.
And manufacturers are complainting too: Nvidia replaces parts of X; Intel rewrites parts of X; ATI tries to work with the existing stuff and it took years to achieve acceptable performance.
Then, why don't rewrite X completely, if the actual one have no good solutions for the modern desktop needs?