Look at what Intel is enabling with Thunderbolt and it will be clear that all the pieces of the "PC" can be easily separated with a simple wire between them. This means you can plug as big of a processor into "the accessories" of interface, that you need. It also means you can plug as many of "the accessories" as are necessary. So, don't be too surprised when there is a Thunderbolt port on a future iOS device and you can just drop it into a dock and use it to be the "processor" for lots of things.