"I'm not on facebook" is a very proud statement among almost every teen or tween group nowadays atleast where I come from (India) and more often than not it is followed by a "Oh nice".

Apparently people have really started getting over facebook or atleast for many of them it has remained as a contacts manager and a messenger.

In my opinion the solution is not another SN like G+ but a better, more refined and faster way to communicate electronically.