Yeah but it's a port.
The PSP already proved it could sell a GTA game:
I'm sure Chinatown Wars on PSP sold several million copies on PSN like MGSPW does. No PS3 or PSP games would ever sell bad cause we never know PSN sales and every game is selling like hot cakes on PSN.
MikeB predicts that the PS3 will sell about 140 million units by the end of 2016 and triple the amount of 360s in the long run.