If we approach it spatially - in terms of context of use I mean, rather than the device itself - it becomes clear why I think it’ll be a success.

It’s a device for airplanes, taxis, public transport, park benches, coffeeshops, pubs, bars, bistros, co-working spaces, breakouts, studios, receptions, meeting rooms, plaza and piazza, public libraries, beaches and all manner of transient spaces, civic spaces. 

It’s a device for cities.

 It’s not that it couldn’t be used in rural environments of course; just that it wouldn’t be. The general lack of third spaces in such places means that a phone and a PC are sufficient. By living in cities, in other peoples’ places, a different kind of device becomes appropriate. Something light and small enough to fit in a handbag or satchel, yet powerful and productive nonetheless. In the old view of city living - say, the classic Parisian apartment - the small size of dwelling meant that the bistro downstairs at the street level of the block becomes the dining room, the bar/coffee shop becomes the living room, the shared courtyard becomes the garden, and so on. While this vision is hopelessly romantic, there are numerous urban variants on this kind of living, and these transient (yet personal) spaces are where the iPad will fit right in.