It’s incredible how much they’ve integrated FB into the rest of the web. Hell, there are people out there where FB is the ONLY thing they do on the web; it’s essentially their own little internet.
I’m not sure how much life FB has left to it, but I can’t see it going away any time soon for individual users. What I am seeing (reading) is more pages / groups talking about leaving for various reasons. The obvious problem with that is being able to reach those individual, lifetime / fully integrated FB users.