facebook is merely a service that will exist till some better service comes along.
disclaimer. never had a facebook account.
The inevitable comparison when this comes up is to Friendster or MySpace, but it's really a poor one. Neither had anywhere the reach of Facebook even at their height, nor a large percentage of the world's internet users. Earlier social networks had significant competitors. Isn't it remarkable that in the ~4 years that Facebook has been dominant, _nobody_ has successfully challenged it?
Facebook will likely diminish in importance at some point, but it's not going to happen any time soon.
I don't think Facebook is a "fad" but I do think that it has a shelf life. It annoys me. I do get to keep up with the lives of people I once knew... but it annoys me. And honestly I'm not sure what annoys me more, Facebook or the people that treat Facebook like the Golden Calf. I would rather be on G+ but their lack of a full feature API is a barrier.
lol
It very weird to watch a American society buy stock in the very company that is trying to enslave them.
Having lots of capital might have enabled Facebook's short-term success, but you need a lot more than capital to sustain a compelling product and maintain a market over the long term.