I think it's going to sell less than NSMBDS because the handheld component allowed for multiples per household. I think this could be a faster hit than NSMBDS.
Sequels to big evergreen products usually have a larger opening, because the audience that was slowly being introduced originally then tends to make an earlier purchase.
The "it's going to sell for a year" based on the original is just a great card up the sleeve for being able to say "wait" in case expectations aren't met. It gives you sometime to come up with plan B. However, I fully expect this game to be slightly more frontloaded than most people are expecting.







