Very weird - in the last 6 months at least, every single person I know of has bought a 4K TV when replacing their current HD one - 40" 4K 3D TVs are less than £500 now. Why would anyone *not* buy one when getting a new one? Maybe it's different in the US?
This is why they say "anecdote is not the singular of data". Your group of friends likely is not a good statistical representation of the consumer population as a whole.
That said, 4k TVs carry a substantial premium when comparing sets of comparable build and processing quality. Yes there are "cheap" 4k TVs, but they are one and a half times to twice the price of comparable-quality "cheap" sets. For instance,
http://www.bestbuy.com/site/vizio-m...lack/3733004.p?id=1219597974182&skuId=3733004 (43" 4K Vizio low-end model, $550 on sale, next week back to $600) vs
http://www.bestbuy.com/site/vizio-e...lack/3417048.p?id=1219581289762&skuId=3417048 (43" 1080p Vizio low-end model, $380) and if you are going low-end you also have less mainstream manufacturers like
http://www.bestbuy.com/site/westing...lack/9660157.p?id=1219705740805&skuId=9660157 (43" 1080p Westinghouse low-end model, $280). Going from Best Buy to warehouse clubs like Sams or Costco and the price differential is even wider because the low-end 1080p name-brand sets are super cheap. On the higher-quality end, the price differential between a high-end 4K and a high-end 1080p set is almost always 2x still.
Take into account that the 4k standards are still just barely stabilizing - a set bought today may well not work with the 4k service you use five years from now - and that there are more game-changing advances on the cusp that will be in play in the next couple of years - HDR and high framerate processing - and that extra cost isn't necessarily "worth it" even in the "long run".
That all having been said, there is a remarkable paucity of actual data. Looking up 4k adoption statistics and I see a lot of assertions from manufacturers at CES 2014 and even a few exec statements saying it will be "huge" as late as last August (1 year ago), but very little analyst interest since 2013. While lack of analyst interest isn't an iron-clad indicator of lack of consumer interest, it isn't good news. When the TV industry holds a party and the paid shills don't even show up, it's not good news. If you ask me, consumers have grown a bit weary of the constant parade of "next big things" when it comes to TVs. HDTV was great. Then 3D. Then "environmental lighting". Then curved. Then 4k/UltraHD/etc. Bust after bust.
Now, that said, predicting the future is much more difficult than diagnosing the present. I think 4k will take off, at least in the ultra-large displays. 4k makes a lot of sense if you take a room setup which was comfortable with a 1080p 50" screen, leave the seating where it is, and just hang an 80" screen in its place. Assuming you had been able to see the difference between 1080p and 720p at the distance you were sitting, making the screen that much larger you'll start seeing pixelation at 1080p. Then, the "4k" experience isn't so much "so much more detail" but rather "so much more enveloping" (because it fills your field of view instead of sitting at center). Alongside this, as with all technologies, eventually it becomes cheaper to manufacture, both because more people are buying them and because the underlying tech becomes cheaper over time.
IMHO, the question is if 4k becomes more important faster or if HDR usurps it in the parade of next-big-things (then 4k HDR comes along afterwards). Personally I'm a much bigger fan of the latter, although the standards there need a lot more work than the 4k standards.
Okay, on to the AppleTV. If the box is in the $100-200 range, I think that you have a different "future proof" expectation than if it is $200+. If it is sub-$100, it is in the "disposable" realm; so long as it supports what I have right now, I can get a new one when I get a new TV (and by then maybe it will support the new TV's features). In the 100-200 range I'm looking at what I'm likely to do with a TV in the next two years and wanting it to support that. For me, that's still not 4k support, but 4k would be a positive selling point at least. Above $200 and it needs to support the high end of the TV market because that's what I'd expect to be buying if I buy a new set in the next five years. Yeah, those price ranges seem a little compressed - a difference of 2x takes me from not really caring about future-proofing to really wanting something that can last - but consumer psychology is often irrational.
TV, THEY could be the "real delivery system".
