i think the probability that satoshi is either dead, or that he destroyed the private keys to his early mined BTC, are high. he acknowledged the implications of mass adoption (extremely high prices), but he seemed genuinely uninterested in making money off BTC.
In my opinion Satoshi might still be alive and he might be slowly selling his coins backwards.
Basically if he sells the BTC that he mined in 2009, then its very easy to track him down and with all the wealth he possesses he might get tracked down, kidnapped, or even some governments might want to have a word with him.
He solo mined most of his coins in 2009, but how do we know if he didn't GPU mine some coins in 2010 with a mining pool which would of made the coins harder to link to him.
satoshi came off pretty altruistic. given the lack of miners in the early days, why would he have any need to pool mine in 2010? anything is possible, but i sort of doubt that scenario given that he said this:
We should have a gentleman's agreement to postpone the GPU arms race as long as we can for the good of the network. It's much easer to get new users up to speed if they don't have to worry about GPU drivers and compatibility. It's nice how anyone with just a CPU can compete fairly equally right now.