I like the idea of having to work to become mayor with maybe a very loose plot, and that as the ending, like others have said, and then maybe the gameplay changes with new features with your power as mayor... As long as they keep the "do whatever you want, whenever you want" at your own pace, I might be into that. Like, the game won't bug you to become mayor if you don't want to, I suppose.
I was kind of in a fluffle about it at first, but I'm warming to the possibilities. How it actually comes out, though, remains to be seen...