Don't know. I'd assume based on his unwillingness to take credit publicly for anything, he was middle-age at least, with an exceedingly small group of personal friends, an introvert, etc. If he was 45 in 2009, he's 60 now. If he doesn't break cover by 2040 he's likely dead, assuming he's not dead already.

If you put a gun to my head and counted down from 10, I'd say he's already dead. If his coins don't move this century and bitcoin becomes the world's base layer money, then one of the first things a quantum computer late this century (one that's strong enough to run something like Shor's Algorithm) will do is hunt those wallets. As a matter of fact, it could become a bounty and massive incentive structure that speeds up the innovation around various qubit entanglement methods. For this reason, I disagree with the emissions arguments around BTC.