Hey interesting thought. I was just talking about that today, but I haven't looked into FB and blockchain at all.
What I said today was, "if FB comes out with a coin, I'm buying it bc those weirdos are trying to take over the world"
Now, that was just me talking to a friend. Not my professional opinion.
I'd have to do more research for a good answer.
I feel like Facebook has a ton of influence and eyeballs, so anything they do will have a good chance at adoption. The main issue they'll run into is trust. Millenials already dislike facebook in general and I don't see them gaining that trust back.
My opinion off the cuff is that, facebook will slowly lose it's influence, but will remain in the game long term. Maybe something like we saw from Hewlett Packard.