The FF exclusive games are a big selling point for the consoles in Japan and probably the States, too. I also believe that some of the larger titles should remain one-console exclusive for at least a while, in order to promote that console - or the diversity of consoles. Why would anyone buy console X if the same games were available for console Y?
Some competition between the consoles is win, ergo, exclusive titles should remain.
As for a full remake, it'd take them 3 - 5 years to make it for the current generation of consoles, and I can't even begin to imagine what it would take for the next generation. Assuming they'd be a step more advanced than the current generation, like the PS3 was compared to the PS2. I have my doubts about that btw - Nintendo made a console with relatively simple hardware and is the Great Epic One in terms of console sales (not so with games btw), and I have a pretty good hunch that Sony and Microsoft will follow in Nintendo's footsteps, at least a bit.