What about the struggling sales (relatively of course) of NSMB2? Could that trigger an alarm?
My guess it's that it depends on Nintendo's level of success of the game, if they hope New Super Mario Bros. 2 sells the same as the DS and Wii ones (which I highly doubt it will), then I guess they will try to change the formula or not release a New Super Mario Bros game for a while. If on the other hand the overall sells of the game are acceptable for them then Nintendo will continue with the series only adding some few changes here and there.
Nintendo and PC gamer