I don't remember nor didn't use myspace, but how did that come to and end? We're there early tell tales like this one?

The collapse for Facebook would probably be very fast once a trigger point is reached, they're kind of all or nothing, they need large data amounts to have any quality to serve ads, if they have less advertisers and data, they won't be able to charge the same prides, it's would be a cascade or spiral moving pretty fast.

Of course, once it happens, fb might be replaced by something even worse, the cynic in me thinks.