if i were PayPal, i'd be much more concerned with Facebook Credits than with Bitcoin - at least for the short term.
Will facebook survive google+ ?
hard to say. google has certainly had their failures, recently - but they're pushing a lot harder on google+ than they have on anything else. i think they underestimated FB for long enough to be put at risk.
but the thing is, Bitcoin will be - essentially - fighting for market share with the big boys. and when you get right down to it, most of the advantages that we all know and love are irrelevant. what Bitcoin has going for it, out there in the world of Aunt Tilly, is
no fees. and that's
after you deal with the drawbacks: complexity, poor UI, perceived security, etc.
i'm pretty big on Bitcoin, and seriously invested - but i'm not going to bury my head in the sand. i need to get off my ass, just like everybody else.