I doubt it would happen. Straight ports of 2D games would probably be easier than 3D games. FF7-9 might be doable since the PSP is a powerful little piece of hardware and may be able to handle the games if they're just ported directly, but I doubt they'd go making many changes or adding a lot of extras since it would cost more. FFX/X-2 and any other PS2 game would likely require reworking since I don't think the PSP is quite as powerful as a PS2, so they're pretty much out. Not to mention anything from FF7-10-2 should be fairly easy to still buy used. FF3 is already being totally remade for the DS by the way. But since a good chunk of those titles probably couldn't be straight ports, I doubt you'll ever see this happen.