It’s not a big deal that PS Vita will be superior than the predecessor PSP. But will PS Vita make people totally forget about PSP? I doubt that. Vita’s capability of communicating with old PSP is one of the reasons. It means that if same game is present on both the handhelds at the same time then it can played together using the ad-hoc mode.
Since many games are downloadable from PSN so there are plenty of possibilities. But, wouldn’t it reduce the value of PS Vita? It should not as PS Vita has additional features that are not present in the old console. It’s just that if you also have a PSP, you can use it with your new handheld to play games together with your friends or family. So what do you think? Good call by Sony or it does not impress much?