The real satoshi could easily prove he's the one. He could for instance log into his forum profile (https://bitcointalk.org/index.php?action=profile;u=3), but I think you're right, he's not going to reveal himself. Maybe 50 years from now, someone buys a house and finds a drive with Satoshi's original walled stored in the wall and we'll find out who he was and where he lived.