Satoshi could have already destroyed the majority of the coins he mined from the early days of Bitcoin. Here is the logic: It's highly unlikely for him to spend the coins mined from the early blocks because doing so may reveal his identity. So, even if he hasn't destroyed his early coins, he probably would never spend them. Thus, a descent amount of coins should be subtracted from the twenty-one million coins that will ever be existing. This will increase the value of each and every coin you and I own.
Probably not.
He can keep them as an investment.
He can spend them in "trusted" or anonymous services that will not reveal his identity.
