People would either need bigger TVs and/or to sit closer. It's the same with 1080p vs. 720p.
Ironically, I might be better able to make use of 4k video on a computer since I sit so close. I find video to be a bit soft on the iPad 3 and Retina Macbook Pro because both have to up-convert 1080p video. I expect to have a 4k or so 27-inch monitor in a few years, and would love to be able to watch native video on it.
I would need to both sit much closer and need a bigger TV to make use of 4k video. I still have a 720p plasma because where my couch is, it's almost impossible to tell the difference between 720p and 1080p.
Some of the detail may have been lost in the compression and some in the upconversion so better source compression and better upconversion may help a lot although more resolution is always nicer.
Ironically, I might be better able to make use of 4k video on a computer since I sit so close. I find video to be a bit soft on the iPad 3 and Retina Macbook Pro because both have to up-convert 1080p video. I expect to have a 4k or so 27-inch monitor in a few years, and would love to be able to watch native video on it.
I would need to both sit much closer and need a bigger TV to make use of 4k video. I still have a 720p plasma because where my couch is, it's almost impossible to tell the difference between 720p and 1080p.