Obviously, nobody knows, but I think Harbaugh has already proved himself. Jus know the history of Harbaugh and watching the 49ers every week tells me that they are going to be good for a long time.
Fundamentally, they are excellent. The playcalling is excellent. Defensively, they are stout. His coordinators are all very good and the team plays disciplined and executes extremely well.
Alex Smith is still the same Alex Smith. He's not a great QB, but Harbaugh has him playing excellent. As long as they have that D and running game the 49ers will compete for the NFC West every year.