You are incorrect. Not that you are completely 'wrong', but technologies take years to develop, and often many more years to bring to market. Blu-ray took about 3 years to bring to market after being bantered about for several years prior to that. It is actually a product about 5 years into itself, yet is still struggling against a competitor (HD DVD). So, we run into huge issued with new formats, like "Can we make money on this?" - That's the biggest one of all. If there really isn't a huge lot of consumer demand, then it goes to the specialty arena, and it will be devloped, but not at mass consumer levels.
FYI: 4K resolution is already used in digital cinema with projectors available that are 4086 x 2160 - they are in use. UHD more likely will be 4x 1080p - or 3840x2160 as you noted above.
This is what 100 grand will get you...
http://www.projectorcentral.com/Sony-SRX-R110.htm
This, on the other hand, is just incorrect. The human eye is only capable of actually resolving a certain amount of resolution. But, the fact that you believe that the impossible is possible, I guess it would sell.
Just not likely anytime soon.
FYI: I did work on a project utlizing 3200x2400 resolution which used video wall processing technologies and four headed video cards with four displays for strategic mapping - it was pretty nifty, but slow as heck. The processing power simply isn't there yet - and this room ran about a million bucks.