4K will never be a mainstream home entertainment format. 4K is format that is strictly meant for movie theaters.
They have to sit that close (probably even closer) to experience the full 4K image. Another reason 4K is only meant for movie theaters.
Sharp is the only manufacturer that makes the 70in, 80in, 90in and I think 100in model TVs.1080p has already looked for those with 2560x1440 or 2560x1600 monitors.
Expect to pay about 5 racks for that TV until Vizio comes out with something similar to undercut it.
Not too many other manufacturers make LED/LCDs over 60 to 65in.