I agree. If you change the title and nothing else, then if anything, you're most likely going to lose sales, because in all likelihood, only fans of the series would realise it's the same game under a different name. And not all fans might be aware, so those fans will just assume they stopped making the game. And yes, if they change the game too much, like I said earlier, it'll be the death of Final Fantasy, not just as a title, but as a game. Right now, Final Fantasy is successful. Until there's any sign of that changing, all Square Enix need to do is worry about keeping the stories interesting, and perhaps keeping game play fresh. If they do that, there shouldn't be any need to change the name. I talk too much...
you do talk to much
one more thing i am a fan of the undertaker aswell