Only if they can shake the NSMB brand. It should probably stay 2.5D, but it needs another rebranding the way the original NSMB did. Maybe even a moderate shakeup in the formula. NSMB is just too stale. It was one thing when it flopped on the Wii U, but it had no business doing worse than 3D Land on the 2DS. Something is definitely wrong. The series needs some kind of shakeup. And hey, a new style like that will give Nintendo another Mario era mode to put into the next Mario Maker, which would be fun. I've a feeling the next Mario Maker will be an explosive jump in sales from the first as well.
I agree with all of this, but NSMB2 actually outsold 3D Land by a bit though. It’s only 12.12m against 12.70m but still.