As for res....I have yet to see 1080p on anything higher than my dead 47". But I would imagine it's possible that huge-ass screens would do with an even higher resolution. Who wants to watch The Dark Knight on their 200" wall in measly 1080p, when they could be watching it in glorious 4320p at 300hz!
Cron can back me up on this, I have the 67" and he has the 61"... and 1080p24 at that size is AMAZING.
Yeah, I agree that anything over 100" could use a higher res, but what size of market would that be compared to the billion folks running an average size of 36"? A grain of sand in the beach of home theater.