Probably what will happen is that FF will stay on the PS3 and get respectable sales there, while all smaller RPGs will go to the Wii (that won't have the competition of a main FF game). FF will continue to sell decently on the PS3, though maybe no up to it's predecessor, while an almost broke developer in Japan makes one last game that's an RPG for the Wii, it becomes a massive hit, and by next generation, FF is all but a distant memory.
Or SE might just make a new IP RPG for the Wii, which would probably be a hit, not "ruin" the FF series, and still tap the market. Win win for everyone.







