It will not become a universal currency for me, because I will never use Facebook Credits. I refuse to do anything actively to monetize Facebook. I'm happy to interact with my friends there, and that helps keep my friends on Facebook's social graph, but that is the most I will do for Facebook. Either Facebook will monetize through other users and keep going, or it will fizzle out like AOL and MySpace. Either way, I know how to keep up with my friends.