It will be the same thing as the iPhone -- iPad.
The iPhone is actually the "lead" platform really, the iPad gets the same chip, just beefed up in cores/RAM occassionally so it can drive a higher resolution screen.
But keeping them mostly the same (same chipset more or less) allows iOS devs to port (or really "upscale" their games) easily and keep the experience the same more or less.
The consumer is free to choose on what device suits their lifestyle best to use those apps/games on ... that's what's going to happen with Nintendo "consoles" (though I don't think they will resemble consoles anymore).
This model could also enable faster hardware refreshes too ... if the software library is effectively "liberated" from being a slave to one platform, and the platform is really just up the consumer's taste (whether they want a tablet form factor, a cell phone form factor, a home TV form factor, etc.) then the hardware can be refreshed more often.
