We're close. Online cam performers are taking bitcoins for sessions/requests. There's at least one subreddit for this, though I can't recall the name, having stumbled across it with the /r/random page.
It wouldn't surprise me if bitcoins were already being exchanged for escort service or some kind of "hookup" business via side channels already.
No, seriously, once a currency gets to the point hookers accept it, it's indisputable that it's real.