Digital television is ALWAYS compressed.
It will require 4 times the data throughput as it is only 4 times as many pixels. Period. There isn't a downside. If it is only getting a 1080p signal then it will be at least that good and you know that they will have a lot of processing to anti alias the upscaled image. It will probably really help on 3D movies where they are cheesing out by cutting the vertical resolution in half.
The only issue will be getting the infrastructure caught up with it. The cable companies may have a problem but if they don't take care of it they will go the way of the buggy whip because the Internet and Netflix will scale to take care of it.
The only real issue that 4K may have is if it makes enough visual difference that anyone will care enough to pay the premium. I really think the only place it will really noticeably shine is 3D. We will just need to see how fast meaningful 3D content becomes available. And with the limitations on how much 3D content you should reasonably watch in a day that will slow the "need" for it.