I believe that Satoshi Nakamoto has a higher probability that he is only ONE person, since if it is a group, there is a much higher probability of this information being leaked.
Also there are theories that Hal Finney IS Satoshi Nakamoto.....with Satoshi's disappearance coincident with Hal Finney's pass away.
That is what most people believe and i think it is a fair assumption .I mean who wouldn't have touch all those bitcoin by now any human live would have by now .Just curious did anybody go through is old computer trying to get excess to then