"Currently there is no "successor" to Facebook". Well, of course there isn't. And there wasn't a successor to Myspace for a while either. What we are saying is that we "can't imagine" a successor to Facebook, because, let's face it, if we could we would certainly build it. But the way these things work is that something will come out of nowhere and we'll immediately feel like we "need" to be a part of it. It will fulfill a need we didn't even know we had. Oh, there will be something that knocks off Facebook and probably Google as well.