I think Wii U is selling 28-30 million total. The amount of casual gamers coming back that you have is highly optimistic IMO, that ain't gonna happen.
Mario Kart 8 - 9-10 million
NSMBU - 7 million
Smash Bros. U - 7.5 million
Super Mario 3D World - 6.5 million
DKC: TF - 3.5 million
Wonderful 101 - 150k (sadly)
Bayonetta 2 - 300k
Wii Fit U - 800k
Personally I think Zelda is a declining franchise. Twilight Princess was inflated by the Wii's early success, the next Zelda is not going to have the benefit of that. Expect sales more in line with Skyward Sword or less unless they really do something with the franchise that's mindblowing.