[NegativeK]

For an individual, Facebook's value is in the connections that people have formed on the site. If Facebook was down for a week, there'd be people searching confusedly for the next social platform That Everyone Uses.

Would Plus receive more traffic? Well, yeah. But so would Twitter and other social networks. My mom, for one, would return to sending email jokes instead of resharing Facebook stuff. She doesn't know what Google Plus is. I imagine a large number of other individuals are in the same boat.

Would people return to Facebook after a week? Assuming the connections between users aren't broken, I imagine so. It'd take more than a week to reconnect to that coworker from seven years ago, but who I still enjoy talking politics with about once a month.

So, in other words: Facebook's biggest asset is that it has a crapton of momentum. Keeps its one billion users on the site more and more is going to keep that momentum up. Switching from Facebook to the new thing would be more of a collective hassle than the demise of MySpace. That doesn't mean it won't happen, though.

[hellosmithy]

Metcalfe's law. This is really pretty valuable though. Not many people are likely to hang around on an empty social network no matter how great the UI. Personally I'm pretty fed up with Facebook, but living abroad it is still quite simply the easiest way for me to stay in touch with a lot of my friends.