In classic Apple fashion, HD is "Good Enough" for now and it appears that their next Apple TV won't support 4K streaming. I guess I don't blame them. 4K TV sales have been flat right? Oh, that's right - they are selling like cotton candy and the county fair. Maybe it's because the internet can't handle 4K - or people can't tell the difference. Either way, if this is true, it's a stupid move by Apple and one that may have some customers demanding better viewing quality through Roku or some other competitor product.
Moreover, very little streaming content is actively available in 4K, especially from services supported by Apple TV. Sure, you can watch House of Cards and a handful of movies in 4K on Netflix (provided you have a TV that supports 4K streaming on the service), but the library of streaming options on Netflix, YouTube and Amazon Prime is limited at best. In fact, the amount of native 4K content is reminiscent of the HDTV landscape in the early 2000s.