I have issues with calling games from the generation just before the current one as classic. The 16bit era and before, sure, but I think it's a little too early to be naming N64, PSX, or Saturn games as "Classic."
That being said, Mario 64 was certainly a genre maker and definer (and still is in a lot of ways), and down the road will probably be looked at as revolutionary as the original SMB. For now, though, no, it's not a classic.
daroga