This should be an easy win for Mario kart despite the head start NSMBU has but then if Nintendo does a bundle for christmas of Mario kart and NSMBU with the console then it gets more complicated.
At this point I'm not sure how large Mario Kart 8 is so unsure how easy it would be to include a download code with a wii u console but NSMBU is an easy download code pack in which obviously Nintendo prefers.
We don't know the review scores yet but it goes without saying that Mario kart 8 seems to be by far the best game on the wii u so far in visual beauty and new ideas. NSMBU is just a tidy up of a wii game. If Mario Kart 8 had been a launch game and bundled with the console the wii u probably wouldn't be in the mess it is now.
Mariokart 8 is likely to be the no.1 reason to own a wii u.
