One big reason the Playstation brand is still kicking is because it was a strong brand for their first 10 years. Typically, if a consumer bought Playstation, they got all the games. That isn't happening now.
Sony is starting to hit a dilhema that is going to prevent them from ever being on top again. With systems being more and more powerful, cost are rising faster then revenue can keep up, and with weaking world economies and growing disinterest with videogames. people are less willing to buy videogame systems, esspecially when they run somewhere from $400-$600. Sony was successful in part because they had all the games and launched early enough to take all the third party software and build a sizable userbase. But if the other guys launch first, or right around when Sony does, this advantage is gone. Now, it depends on what software you do get. This means 1st party software is king, and we know which company wins that war (hint: it starts with N and rhymes with go). Sony is not a game company, so all game studios they own they buy. The same is true of Microsoft. This also means that all first party titles they make are only just as good as other first party titles on the market, so it becomes a game of moneyhatting and luck that they bought the guys who will make hits. This is going to put the ball in Nintendo's court every time (the only X factor for them is getting third party support, but they've proven they don't need it so long as their software is top notch).
If I were Sony, I would not bother with a PSP2 now. The 3DS has sucked up the support so Sony has to hope for scraps. They also can't compete with Nintendo's first party titles. I would only release a PSP2 when the 3DS infringes on the 3D market Sony is building in a hjope to stop Nintendo.