Licenses are permissions to use a privilege which some legal rule (e.g., copyright) makes exclusive. You don't need a license when a work is out of copyright.

Its funny to be relying on copyright licenses when what people really want to to do is rewrite the law, but that's a different issue.

I'm saying the copyright on the license will expire, at which point the parts of the license that rely on its own copyright will no longer be enforceable.