Judging by the price drops in large TVs and an upper limit to increasingly larger displays, I think the business is ripe for adding features through software instead of purely hardware considerations. A TV box makes more sense for people who already have TVs, but an integrated device will work better and is Apple's modus operandi.
HTC, Samsung, and others can make considerable changes to the Android interface and features, while I bet win8 on any phone will be about the same. I don't think Nokia wants to compete with Microsoft on phones with nearly identical software.
Apple doesn't offer a feature phone, so they will continue to pick up customers from people looking to upgrade. Smart-phone's apps and media lead to increased customer stickiness, while feature phone customers are prime for switching to Apple.