I hold the opposite view, Facebook itself has lost social momemtum to Instagram, Twitter and others, and this is eroding their grip on the high value parts of the social graph.
Instagram seems to be coming up a lot as a place people are leaving to from facebook. It’s owned by facebook. I wouldn’t say that is eroding facebook’s access to social data as much as it may seem.
But Instagram is FB too so they are not losing anything. People link their accounts and friends and the social graph continues. They push FB connections into IG pretty hard these days.
You know Facebook owns Instagram and WhatsApp, right?
I know, but the point is social networking sites are ephemeral, owning the social graph of older social groups does not ensure dominance of younger social groups.
It does if they they have the same backend.
For example, Facebook and Instagram each use your network from the other to for friend suggestions.