Of course he expect bitcoin to last very long since he created bitcoin
Where is the logic in that? I think he was well aware that what he created was an experiment and still is. Nobody, not even satoshi, could have predicted what would or will happen in the future. I'm sure he's probably both surprised and proud how far bitcoin has come.
Predictions and expectations are not the same thing. Satoshi did expect Bitcoin to be successful. You can perceive that in the whitepaper and in his messages to public groups.