Comcast/timewarner/and cablevision all have software that you can use on an ipad or ip[hone to watch tv.
Apple does not have to do an new setup .Just have those 3 put the software on the apple tv. No new setop required.
Cablevision showed their software running on a samsung and lg tv so why not?
There is no Apple TV developer agreement other than those very specific ones (eg Netflix, Hulu, etc). Apps running on iPad wouldn't automatically be supported by a 4th gen Apple TV. The developers for the MSO would have to do that.
And if Apple tries to support it themselves, MSO simply pull the apps from the App Store.
Apple has no real choice but to negotiate with MSOs if they want to deploy a 4th gen Apple TV with apps, games AND cable TV.