The very same question was raised when FFX-2 was announced. And for that series, I thought that FFX wrapped up very nicely and just because (SPOILER)Tidus "died" doesn't automatically warrant a sequel where he had to be (SPOILER)brought back

Anyway, SE knows that everyone loves FF7 and I think it's obvious that they're trying to milk some more money out it. Kudos to them, I know I'd do it if I were them. You're right in that Vincent's a very vague character and this means SE can basically do anything with him. More likely than not, it'll have nothing to do with the original game except for a couple of people and place names.

I don't think there's enough information out right now for me to decide whether or not I want this game. But from what I've seen, it's going to look more like a game of DMC than a game of FFVII. If I do decide to buy this game, it will probably be because I enjoy dark, many-a-zombie, action shooters and not just because it's a sequel to FFVII.