There was a hardcore set of videophiles who were buying Sony Trinitrons [HD resolution] till the bitter end. I have an 1800x1440 Sony Trinitron I use as the secondary monitor on my workstation [mostly when I want to play videos]. However I haven't moved the thing since the winter I was still young and recently employed in manual labour.
I don't really understand who the market for '4K', etc, TVs are supposed to be. Most people sit at least a metre from their TV and can't make out pixels at 1080 res. Computer monitors on the other hand... I've waited almost my entire life for monitors on which I could no longer differentiate the pixels. I'm getting old enough that this might happen owing to developments in my biology rather than technology.
I would have bought the 5K iMac already if it weren't for Apple's non-standard [Frankenstein?] solution to video bandwidth. I'm waiting for proper DisplayPort 1.3 support — probably in the next generation of iMacs with 'Skylake' chips later this year.