You know who currently has an even better advantage in social networks? Cell phone carriers. If I take a look at my Facebook friendlist or feed, and compare it to the last calls and messages made on my cellphone -- they don't match up at all. That means, at least to me, Facebook's graph for me doesn't relate at all to my real world social network, and so most of its value is probably artificial.

Certainly no system ever built can match Facebook's penetration rate, but it will probably always pale in comparison the real world social network. The difference is mobile devices are going to map a lot better to the actual network in ways that Facebook will be unable to capitalize on.