If FB suddenly disappeared, I'd lose almost all my good friends and acquaintances. And it would be hard or impossible to find them all again; they're scattered around the globe, mostly FB is the only contact point I've needed/had, dont have their phone, email or address. I should get that info, huh. On FB I almost exclusively just chat with friends.

Never used Twitter or wanted to.

ps Why would the world fall apart if Google disappeared? It's not obvious to me.