If Sony is going the gaming phone route as a PSP successor, then they're kind of taking themselves out of the running of evening competing with the 3DS; it's a somewhat different market.
That said, I want my portable system to play games. I don't want it to come with a 3 year-contract for an overpriced phone plan, or cost $100 more if I don't want a contract. I don't see such a device working for me; at all.