The problem with it being Hal Finney or any of the other known characters is that it doesn't add up: why would anybody want to keep it a secret? And why wouldn't they cash in their $60 billion? (Or, if they lost their keys to the 1M Bitcoin, why wouldn't they just say that and help the price of Bitcoin?).

And remember that this wasn't always $60 billion. Even when Bitcoin was at $1000, somebody would have to turn their nose up at $1 billion--or even less. Had the holder of the 1M Bitcoin been alive and owned it personally, they would have started selling when Bitcoin was $100 or less most likely.

For me, the only possibilities that are plausible is that either Satoshi is dead or he is CIA/NSA. Only a government (and frankly, only the US government) could let $60 billion just sit there.