I just want a "dumb" screen and then a cheaper box that I could swap out as needed. Screens don't change very often... but playback hardware certainly does.
Actually, playback hardware don't change all that often either. Video game consoles, for instance, get update roughly once every 7 years. That may be longer than TV, but it isn't as often as one think.
Don't get me wrong, I think Apple should continue to make set top box, but I think there's a big market for integrated TV set as well, especially those that have grown to love Apple's industrial design and fully integrated ecosystem.