There's one big impediment to X11-Light that does shout back to my issue of design it out, spec it out, write it out. And Daniel hit on it during the talk, X has 3 API's for input...and they are all inter-dependent on eachother. It frightens me to think about other spots in the Xorg stack where we have a similar issue where API's are inter-dependent on eachother AND redundant of eachother. So just "taking out the old stuff" does not necessarily work. Certain parts of the stack WOULD have to be redesigned and rewritten to make sure the code is clean at the end.
exactly
it wouldnt work nor be enough, when looking at the at the "X12" proposal (or the "Why X is not our ideal window system" paper), you realize that certain aspects of X are "less than ideal" (when not straight out broken) at the core protocol level (like the 16 bit unsigned dimension / 16 bit signed coordinate model allowing for 32K x 32K pixmaps with 3/4 of their surface unaddressable - or the drag and drop and clipboard model..)
and that if you want a sane and modern infrastructure (especially, one accomodating GPU's as first class citizens) what remains after taking parts away also need to undergo significant rethinking ( at which point it becomes something which is not X any more...)