Final Fantasy (I)-VI were originally on Nintendo consoles, VII and VIII are on PC, and XI is on PC and XBox 360.
Meaning that of the twelve main FFs, only IX, X, and XII are exclusive to PlayStations, and most PSX fanboys I know didn't like IX that much (I enjoyed it, myself). So if they disregard that one game then there are only two PSX FFs...and FF XII only just came out, yet the notion of PSXes being the home of FFs have been around for a while. Three out of twelve? That's a measly one out of four.
Strictly based on that track record, if Square-Enix even briefly considers to porting FF XII and/or XIII, I see no reason why they wouldn't.