so what? I would wager the game is still gonna be boring.... go to point a and then to point b etc. Even after you beat the game you there will be nothing left to do, much like a god of war game.
The only con I would see is fighting. Over 500 people working together to assemble this game, there would be so many arguments, saying that they would want this or that happen, or take what person #463, said, out.
Indeed, as you can see in my post above, that's what I see.More people working on a game, isn't always a good thing.