Well obviously no one knows... or very few people know (I still think that there are a couple original bitcoiners on this forum who are 99% sure that they know who Satoshi is).
Whats your favourite theory?
Mine is that it was John Nash

Please provide some proof for your theories. Would love to look into them!
For some people, Satoshi Nakamoto was unknown. He or she could be a group of people. He or maybe they had founded some powerful entity, to destroy banking system. Hence, maybe satoshi could be dead as of now. Maybe, he didn't really knew that bitcoin will be of successful. Or maybe, he could have been killed because of Bitcoin. Because Satoshi is a person that has no life other than programming.