Real Satoshi won't reveal his/her/their identity, especially knowing how identity-based hate could be used to harm Bitcoin reputation and possibility harmed by authoritarian government.
But that's not the point if this discussion, you didn't thought that this is all just hypothetical? Yes, you're right and you've got a point as to why Satoshi won't go public but it's not the point.
To me, I think that the only proof that Satoshi could identify himself is probably doing a signed message on his address, or logging in his forum account or logging in the Bitcointalk forum prototype (forgot the name of predecessor).
Right. If he can leave a signed message on his address, then it may be a proof of a real Satoshi. His own bitcoin forum account has been hacked already so there's no way he can access that anymore. If he can be the real Satoshi, i think he will do such a thing that we never thought of thinking and its only him who knows that.
However, i'm not really expecting that he'll show off one of these days because its better to make him anonymous for good than to make him known and confuse the whole crypto market.