I think it's too early for 4k on tv's:
1) I don't think average TV size is big enough to warrant it yet. I think 70"-80" tv's are where you start to see a bit of improvement over 1080p? Will it be enough to get people to upgrade? probably not. I know alot of people who only just upgrade to HD sets (or haven't yet). The HD takeover is still in progress. They're not going to sell a new format this quickly. Color SD tv was around for decades. You need a big improvement to get people to buy. If the average TV size is less than 80" 4k won't be a big draw.
2) There's nothing to play on it. The best way to watch movies is on bluray. They only do 1080p. Cable TV only does 1080i (and alot more compressed than a bluray). Online services like netflix, xbox marketplace etc.. compress the crap out of their HD signals. There's not distribution system for 4k content (and may not be for a long time).
I think that's my two big arguments. 4k won't take off until alot of people have incredibly large tv's in their homes. Currently most people I know have 40 or 50inch HDTV's. At some point you just don't have the room. I think it's too early for 4k.