I'd expect about 8.5 million in sales for next year.
I think it will follow a similar pattern to the 3DS ... disasterous Q1 2013 sales, Iwata apologizes to investors, sluggish Q2 2013, Nintendo rolls up their sleeves at E3 and slashes the price by $50, promises 3D Mario + Mario Kart 8 for fall 2013, fall sales are solid. People want the big guns, Pikmin and Rayman don't cut the mustard.
I will also add I think Wii Fit U will be a big sales dissapointment, much like Brain Training and Nintendogs on 3DS (relative to previous installments). That casual crowd is not paying $350 for some new Wii Fit minigames.