I wonder if they will ditch Cell?
I think that PSP2 will be "portable PS4" not PS3.It would make sense,they already mumbled something about single submission for PS3/PSP2 games and there is this whole PSP ports thing,shared saves.
Play the game on one device and continue playing on another.Realistically,you would still need to buy two copies,but they could make some deal--buy one get another one cheaper,devs that go on that route can be rewarded with marketing help,etc
At least they could test the market on some games were it makes sense.
It would make sense to go with ARM like in PSP2 case--put multiple cores,clock them high,boost them a little and find some decent gpu=win