It's expensive. The picture is great. Netflix announced they'll be streaming 4K soon. It's going to be real, and soon. The TVs are 2-3x the price where it will take off. http://www.stuff.tv/netflix/ces-2014/eyes-we-feast-our-peepers-netflixs-4k-streaming-video/news
Interesting. Hadn't thought much about it but with netflix being able to stream it this just might work.
I saw a 4K TV at Costco and the picture was amazing. They are working on bluRay standard for it, and once there are players and content (disks) I think it will start to take off.
The no-name Costco ones are less than 1/2 the cost of the other brands. From what I've read, people don't like them because they are edge lit and otherwise inferior technology. Check out the comments to this review, for example: http://www.engadget.com/2013/11/12/hisenses-4k/ Also, the media is so big it wouldn't fit on blu ray discs. They're not going to sell content on disc for these TVs. You either stream or download to a hard disk and play it from there. The Sony TVs now come with a preloaded (with movies) hard drive and app-store like online movie kiosk.