I was actually thinking about this same thing playing SMB yesterday.
I think WiiWare may be the answer as stated above. To get that service off the ground, you may see a NSMB type game released. It would be a smart idea, cheap for Ninty and sell a ton.
As for NDS, they would be foolish not to release one more Mario game considering the legs that the original has.
Even if they just made more levels based on the same graphics it would be a t least a 3 million seller.
As for the main series, I don't think you'll see a true sequel until Wii2 (or whatever) As someone mentioned above... these games take forever in development.
Predictions For Last Full Week of Sales in 2010)
WII - 80.35 Million
360 - 43.88 Million
PS3 - 41.40 Million
More terrible predictions coming Jan. 2011!!!
