Yes and the announcement of Amazon coming to the ATV would have been an excellent time to introduce 4K support. On the other hand, Apple wants to keep selling ATV devices, and the minute they announce 4ak without simultaneously offering companion hardware, their sales will plummet until the release. Frankly, I don't know how Apple can't add 4K to the next hardware update.
One of the most frustrating things for me is that I have both a 4K TV at work and at home. I'd love to AirPlay stream in 4K for one reason -- so people watching in the room can actually see clearly the information on the screen, from a simple webpage to a detailed excell spreadsheet. As it is, we have the 4K TV which must upscale the max resolution of 1080p resulting in an even more degraded image. And 1080p is simply not high enough resolution for people to easily read most Mac screen mirroring from a distance even on a 65" TV. on the previous MBP with an HDMI output 4K resolution was supported, but that often means running a very long cable to it. The new MBPs require a dongle in addition. We invested in ATVs at work specifically to improve the setup for presentations and impromptu demonstrations, but now that we've upgraded to 4K panels, we've almost stopped using the ATVs.
At home, I'm just dealing with it, rather than unspool the HDMI cable and string it across the room. Depending on what it's is, I will often just use the Android app built into the set. The worst part of it is that I can't even use a wired solution with an iPhone or iPad if I wanted to since they don't support 4K output at all.
