Just to add that the idea that apparent screen resolution goes down with distance isn't hogwash, just that I think the charts that get sent around the Internet suggesting sitting distances for various screen resolutions severely underestimate human perception.
Heck if you follow these charts then you shouldn't be able to read the text on a 1080 21" screen on your computer.
I saw a 4K display while passing a showroom in a mall and had to stop. It was, indeed, stunning.
And I've seen these charts spread around the Internet showing optimal sitting distance for screens of various resolutions. That's probably where this '4K would look best on a TV screen at least 60 inches in diagonal' comes from. After looking at this screen I'm convinced that these charts are complete hogwash. I don't think the screen I saw was 60", and the clarity compared to the 1080p screen nearby was amazing even from pretty far away. My kids, with much better eyes than I have, noticed it without my prompting (and without me telling them what a 4k screen was).
Netflix has announced that they are planning on including 4K videos. And I don't know why our over-the-air broadcasters don't put out a 4k signal. Many people don't realize that in addition to the digital television standard, there's an MPEG4 standard for portable television that many are broadcasting, but I don't think anyone is receiving. They could repurpose these channels for an HEVC 4K signal and over-the-air broadcasting could be revitalized.