So one misconception needs to be cleared up: Just because you raise the money for the rights to make FS3 happen, Interplay is, in no way, obligated to sell them to you. Also, if the community raised enough money to actually do so, there's a solid chance that interplay would keep the rights because you just proved that those rights have a real value.
Anyone who gives money to a kickstarter account that had zero control over what it promises is a fool.
US: Hey interplay! We have thousands of dollars of donated money to buy the rights to FS!
Interplay: Wow! People will pay just for a chance of a game? I think we would rather cash in on that, sorry to all your investors!
What you need to do is secure a business loan and by the rights. That way, interplay still sees it as a low potential product, and will be more inclined to sell it. Once you have the rights, use kickstarter to pay back the loan.
Still risky, but more plausible.