Satoshi is long dead you silly kids, not even theymos or others has ever heard from him since.
He vanished very sudden like he didn't get a chance to further communicate with the community.
How do you know?
Price would drop as hell only in case he sell all bitcoins, but I doubt that he is crazy enough to do something like that. He is definitely very rich guy now, and many people don't have problems with money but their ambition is driving them to wish and earn more. It's not question how rich Nakamoto is, he is rich and everyone knows that, question is what is he doing with all that money, profit he make, what is the next big thing that he plan to create?
This is not a given, by any means
Even if Satoshi wanted to sell his bitcoins, he would most certainly look for an off-market deal. Indeed, he wouldn't be able to get the market price, but he would still likely not get what he might be offered off the market if he decided to sell his coins publicly. So I don't think that, first, he would have problems selling at least decent part of his stash, and, second, that it would necessarily crash the prices. Counterintuitively, that could even boost them somewhat