I think they can. It might take a while to build up a good user base, and make it truely profitable, but they can expect what ever they want. 2 quick examples:
- 1. If people want to listen to iTunes protected music portably they will be expected to (but not forced) buy an iPod.
- 2. If people want to watch HDTV they will be expected to (but not forced) to buy an expensive TV.
If Apple really wants to do this, just price it right and people will buy into it. Maybe price it like a game console where they take a hit on hardware costs, but gain on selling movies.
BUT..
I think the whole Mac Mini Intel thing isn't going to happen that quickly. I predict that come January we will have a Mac Mini with a G4 and enhanced Front Row capabilities.. no DVR that quick.