marginaleye, referencing the MySpace to Facebook to Google+ trend: "I fear, however, the horrible possibility that social networking is going to be a perpetual treadmill of pursuing the 'in crowd' and fleeing prole drift, stretching out from here to infinity."
Well, it is how clubbing seems to go. Some dance clubs do last a while, but the crowd does seem to follow the trendiest new place. So there is some social precedent here.
I suppose if one was creating a social networking site one might keep that particular dynamic in mind.