I still can't quite believe how easily the public gets fooled by 4k. It's been shown time and time again to see it's benefits besides 20/20 (or better) vision one needs to stand few feet away not from 50" screens, but 80" ones. I am at stage on my life that even thinking about price tag on 80" 4k TV scares the crap out of me.
As TLS mentioned - Very unfortunately both Kuro's tech, which later on was blended with high end Panny's plasmas is lost
I recently demoed near high-end Samsung 65" 4k TV - while the image was very vibrant - I could tell easily the calibration was WAY off.
The compression artifacts were horrible, even on Netflix "4k" - it was easily noticeable. The default motion compensation settings were terrible.
DVD was huge step up. BD was a major improvement. 4k?? - A minor one at best and it requires very significant investments to even see
some benefits.
Only yesterday I was watching first season of Seinfeld. It was in 4:3 SD quality. Compressed with H.264 and AAC stereo (175mb for about 22mins episode)
it was perfectly watchable on my 1080p 55" plasma at 14' away. Most action movies are practicably indistinguishable 720p from full 1080p. Only time I do notice any difference is with high quality Discovery content, like "Frozen Planet" BD.
I think 4k, just like 3D is a fad, which I will not pay a dime extra for it (if I have a choice - I didn't and had to buy TV with 3D, which I never used nor expect to ever use)
edit:
Heck, Even most unreliable Tech news source ever , says 4k is stupid:
Why Ultra HD 4K TVs are still stupid - CNET