Facebook will make money, that is the least problem. Facebook connect is going to evolve to merge with MySpace, WindowsLive, StudiVZ, Xiaonei identities. People no longer identify themselves by their email addresses, they do so by their social networking account, and he's right there.
And people don't like changing their social network, they are too entrenched. Americans like to think that Facebook is so dominant, but lots of people like Hi5 and cannot imagine using anything else, because their friends are all there.
There will come a system where people can sign-in anywhere using their personal page. But such systems come slowly because of all the competing interests each pulling another way.