Social networking is not a fad. If anything it's becoming an underlying utility of the internet much like email, instant messaging and search. Any technology that's so core to the internet starts out as a standalone application (hotmail, AIM, Google) and becomes an underlying layer.

Facebook's advantage? They have a virtual monopoly on this utility. Not only that, switching costs are high (unlike email and search).

Look at the kind of growth apps gets from integrating with Facebook (Instagram, Viddy, Spotify). All social apps going forward will only reinforce their position by integrating with them.