The breakthrough will come from reinventing how printed content is distributed.
The secret of iPod's success had little to do with its brilliant form (and it was elegantly unique), but rather iTune's offering depth, simple pricing, and ease of I/O interface. Otherwise, the gizmo would have been an expensive paperweight, like a Zune player. Apple changed how songs got to listeners.
I wonder how it could improve the way print gets delivered. Maybe it's not dependent on replicating newspaper or textbook pages on little screens, bur somehow parsing it so that reading is easier, faster, or otherwise more relevant to the moment of consumption. Could it create book "rentals" like movies, or build a recommendation functionality that tops Amazon's buying algorithms?
Or perhaps there is a gizmo lurking somewhere in the basement at 1 Infinite Loop. I'd pay for a wristwatch thingee that beamed text on the nearest wall. It's not likely, though.
My bet is that Apple comes out with a tablet, but the breakthrough will be in how stuff gets onto it.
Jonathan Salem Baskin writes the Dim Bulb blog and is the author of Bright Lights & Dim Bulbs, coming in November.