Do you think "satoshi" will ever just randomly log in one day and post something?
No. He's still here, I suspect, but retaining that identity was unnecessarily dangerous.
It seems as if that would be the only way for "satoshi" to ever be proven to be who he is.
Now I very much doubt he intends to do this, but there are certainly other and more reliable ways: signing a message indicating his identity with an address that's provably his (e.g. the genesis block reward address), for one.
I agree that he's here and around, he's just abandoned that hot account. No need for it anymore.
Secondly, he still has the other private key to put out messages over the bitcoin-client network notification system; only him and Gavin can do that afaik, so he can still prove his identity and get emergency messages out if need be.