Yet it could collapse overnight. Facebook is doing all it can to lock users in, but in the end everything revolves around a single user just saying that he/she

Yet it could collapse overnight. Facebook is doing all it can to lock users in, but in the end everything revolves around a single user just saying that he/she doesn't care anymore and is out. If the circle of 10 of my closest friends leave Facebook, I would probably leave as well. Many great services have fallen before Facebook.