Number of people with iTunes content or iOS device > people who have even the slightest clue Amazon Prime has videos to watch
Apple has a bazillion people who have bought songs from iTunes. Many of them also buy movies and TV shows. Tim Cook hasn't been talking about how crappy the TV experience is recently to abandon Apple TV. Next year we're going to get HBO and Showtime unchained. If ESPN were to offer a standalone service, the market for boxes like Apple TV and Roku would EXPLODE. You can already get by easily without cable/satellite using Netflix and Hulu. But the providers hold a huge bargaining chip with sports and other live programming. Cord-cutting is gaining in popularity, and Apple will not abandon it.