I'd argue that following the iPod model rather relies on the competition's devices remaining fairly horrible by comparison - none of them ever had such nice hardware, and I never tried one with adequate software to handle several thousand songs on the device. This seems unlikely to repeat itself to me; IMO* the Nexus 7 is an extremely nice little tablet which proves this kind of thing can work, and other manufacturers can take advantage of Android to provide good software, which often let down the iPod competitors.

There is a third option of course; that the market follows neither model that have gone before, and Apple does not win this time. We won't know for sure until after, though.

* Disclosure: I work at Google, so my opinion is not without potential bias.