Well I want one, but then I want pretty much every system that features a Persona game.
I don't subscribe to the theory that iOS and Android have single-handedly killed the handheld gaming market (there's simply too much that doesn't quite work without proper buttons) but you might see future handhelds hewing closer to phones, and perhaps focusing less on raw power.
Not sure Sony'll have another go, though. The Vita hasn't been going too well and I don't think the PSP did as well as they expected, which was a shame as that and the NDS were my go-to systems for quirky games. There's a lot of unique stuff on both of those platforms.