If Mario Kart has an attach rate SO HUGE, this mean that the only reason it isn't selling more is because the install base can'd concete it to do more.
A port of this game in another platform, wuth of course a bigger audience, will definitively sells massive, and i would not say is so crazy expect more than the Wii U version.
Same for Splatoon in Japan.
Smash is a difference story, it already have Wii U and 3DS version... i think it will be the port with less sales, though i still expect it to be massive. Alright, i'll say my predictions:
Mario Kart 8.5 = 8 million
Splatoon 1.5 = 5 million
Smash Bros Switch = 3.5 million
So this would put all games at:
Mario Kart 8 = 17.5 million (9.5m Wii U / 8m Switch)
Splatoon 1 = 10.5 million ( 5.5 million Wii U / 5 million Switch)
Smash Bros 4 = 18 million (9 million 3DS / 5.5 million Wii U / 3.5 million Switch)
