We always wonder who the real master mind behind the name of Nakamoto Satoshi the creator of bitcoin is.But what exactly would make you believe or convince you that "this" person is Satoshi if he/she ever decided to reveal himself.
There might be infinite wannabes and glory hunters wanting to rise to fame ,given the real Satoshi is one among them how would you go on about finding the right person.
At minimum he should sign a message from an address which is known that it belongs to him or move his coins to another address.
And I say this is the minimum necessary because there is always the possibility of someone getting access to his files and then trying to use this as evidence of being Satoshi while they would be just an impersonator, however I think it is safe to assume that Satoshi will never comeback, whether this is because he passed away already, he is afraid of being pursued by intelligence agencies or some other reason, this seems to be the best possible outcome for the market in general.