Yeah, the only real issue is the development time, but you have to consider that fast development times these days are generally achieved by games that don't innovate or are rather short in gameplay/gametime by comparison. Still, I would prefer the games be churned out a bit faster - the speed of three very different games in XIII, XIII-2 and Lightning Returns shows that they can bring games out pretty quickly if they really want to. I know these games all used the same engine which is not a normal thing for numbered games, but perhaps a new engine shouldn't be needed every time a new FF comes out.

Wolf, you're right, I'd forgotten that you specified that the other games could continue as franchises of their own. I still feel that this would only work in the short term and eventually people would stop buying the games, or joining forums to discuss the series. I think original games are what has allowed Final Fantasy to outlast/outnumber any other major game series (bar the obvious sports games and whatnot... and Mario, should you consider him a franchise in his own right).