While there will no doubt be a few attempts to shake up the social networking clique with new entrants, Facebook has a pretty good grip on it at the moment. The recent privacy concerns being discussed here on HN might make people consider switching to elsewhere, but will they actually do it?
The thing with moving to another social network and leaving the old one behind is that you won't find it to be too social without your existing network of friends/family moving over as well. It's a bit of a Catch-22 situation, really.
Of course, it's possible to use your existing networks to invite people to a new network, but in reality, unless people see value in the new vs the old, they will at best politely decline. In Facebook's case, you'll need people's concerns with privacy to outweigh the inconvenience of switching and building a new network.
I've been invited to about 5-10 new 'networks' from people on Facebook or LinkedIn over the last couple of years. I haven't moved partly because some of them look kind of dodgy to be honest but most because I'd simply have to start over again. That's the 'lock-in' that online social/business network tools have.
People need to be convinced that the inconvenience of switching outweighs the existing concerns.
