What networks broadcast in 4K (UHDTV)? None. What cable programmer is using 4K? None. There is no 4K programming for Cox to carry. Sony supplies a few 4K movies with its 4K TVs, but that's about it. Most people say they see little difference between the current HDTV and 4K TV. And the bandwidth issues that would arise from UHDTV on cable? ACK!
Don't hold your breath. OLED TV prices are quickly dropping, and OLED TVs need no change in signal for a huge improvement in PQ. People relate the picture on OLED TVs as being "jaw-dropping." OLED is the future, not UHDTV.