If it's released in 2016, I doubt the next Apple TV will support 4K.
All the factors working against wider 4K adoption today will remain in place in 2016...
- 4K resolution requires a very large (80"+) screen or very close viewing distance to be appreciated
- Most people don't own or have the space for an 80"+ TV
- Mot people don't want to view a 60" TV from 5 feet away
- Most Americans don't have sufficient bandwidth to stream 4K video at good bitrates w/o terrible compression
- Major ISPs in the US are imposing data caps that would make streaming 4K video prohibitively expensive for most
- Very little content is currently available in 4K
The only place that has 4k is youtube and the compression means that there is very little benefit. It looks great on my retina display 2ft from my face but at arms left i really can't tell the difference. However i can see block noise and compression artefacts on all of them. My connection is great and plenty to stream high bitrate 4k but still there is no one offering it.
The biggest issue with 4k is the hdmi 2.0a standard. If you are looking at a tv with that you really are gonna be spending big cash but you will literally not be able to plug it into anything right now. The delivery medium is the internet now.
I really believe that we should just up the bitrates on 1080p first before jumping to 4k. 1080p bluray still blows any youtube video out the water and also 4k streams for 99% of viewing situations.
Though really when has actually improving the things that mattered sold new tech? never, we are being taught to believe 4k is better blindly without questioning how it could possibly be better if everything else is the same.