Nothing. At least, nothing of lasting consequence. Price would drop. Some of you would panic sell, the rest of us would buy up your cheap coins. Net result better wealth distribution (which, I gather, some of you are keen on for some reason?).
Bonus: If this is in fact the real Satoshi (don't buy it for a moment) and he in fact works for a scary three letter arm of the government, he (they) are not going to do any dumping for the above reason.
My friend, please be under no illusions.
If Satoshi dumped his coins.
Bitcoin would go to zero, with hundreds of thousands of coins left to spare.
But he is not going to dump them, because they aren't his to dump. They belong to his employer, a secretive branch of Uncle Sam.
Now, all those conducting shady trades who thought they were doing business out from under the nose of The Man, these people may be getting a little bit nervous right about now, and that might prove not so good for the USD value of your BTC holdings. But you don't care about USD, you only care about how many BTC u have, right?