ubercake :
Unless I'm missing something, a standard HD 1080p stream (e.g. over Netflix) takes a little less than 6Mbps of bandwidth? If a 4K screen's res is 4x that of 1080p (it's actually a little less), even with current compression it would put the 4K stream in the low to mid 20Mbps's which is consistent with information in the article.
I dunno. I've never used Netflix streaming. I have streamed one 720p H.264-encoded movie at about 8 Mbps, and it looked okay. The detail was a little lacking in a few places.
Over on avsforum.com, I've seen comparisons of top teir 1080p streaming quality vs. blu-ray. And as recently as 6 months ago, you could clearly see in the A/B comparison photos posted that streaming was visibly worse than blu-ray.
Is it good enough for most people? Sure, but so is the current status quo. Will a 25 Mbps 4k stream typically look better than a lower bitrate 1080p stream? Yes, if the encode is well done. It just won't do the format proper justice, IMO.
The best-case scenario is that it starts a competition between streaming services & cable channels to deliver better quality. The worst-case outcome is that it kills 4k blu-ray, without ever rivaling its quality.