In an interview with Bloomberg, Reggie Fils-Aime stated that pre-orders of Smash have surpassed those for Mario Kart 8, and that "The launch of Mario Kart 8 has essentially doubled our Wii U sales year-on-year. Our expectation is that the sell-through for Smash is going to be very strong, certainly on par with what we saw with Mario Kart 8. We think the impact on hardware will be similarly dramatic."
Meanwhile, Sony has sold 8 million PS4s, Microsoft has moved 3 million Xbox Ones, and Nintendo has sold 2 million Wii Us this year. We'll see what happens after the holiday season.