EDIT: But the problem here isn't even getting hi-res re-renders of Pixar movies (do-able, if insane), it's getting you to buy a new 8K TV every eighteen months or so. Unless and until someone figures out how to utterly destroy existing TV business models, nobody is going to try and build value-add TV sets. It's a fool's errand.
Once you have an Apple TV you're locked into the Apple ecosystem for as long as you have it. You'll buy lots of tablets and phones during that time that act as interfaces to it.
Edit: Apple are probably the only company that could make an 8k TV and have content ready to watch on it, or at least they are in a position to have have a product ready before anyone else. They could manufacture them at scale to make a decent margin selling them at a premium whilst locking consumers into their ecosystem for years to come.
Most Apple customers don't buy new devices every 18 months. Apple only needs to make customers happy enough (and locked into their ecosystem) so that when they upgrade at some point, they still buy Apple.
Who sits 5 feet from a 42" TV set? That would roughly be a retina display 8000 pixels wide. You are also looking at something like a 400mbps data rates to feed it.
Well, it's 16 times the picture resolution at the same temporal resolution, and you can do a damn fine job with 10Mb/s high profile H.264 at 2K, so … yeah, I guess that's about the right order of magnitude.
EDIT: But the problem here isn't even getting hi-res re-renders of Pixar movies (do-able, if insane), it's getting you to buy a new 8K TV every eighteen months or so. Unless and until someone figures out how to utterly destroy existing TV business models, nobody is going to try and build value-add TV sets. It's a fool's errand.