If Nintendo can get games out at a similar pace to the actual Wii U and there are more third-party games (but likely not as many as Xbox One and PS4) then you're looking at N64 sales at least, possibly SNES or higher.
Nintendo wouldn't get anywhere close to 100 million in most cases because the console would be too similar to the competition. Nintendo's Blue Ocean strategy is high risk, high reward if it succeeds. DS was earth-shattering, Wii was a mega hit, 3DS ended up as a hit, Wii U tanked, Switch is more in the earth-shattering category.
A more normal 8th gen console sells better but probably not to mega levels.
Lifetime Sales Predictions
Switch: 156 million (was 73, then 96, then 113 million, then 125 million, then 144 million, then 151 million)
PS5: 115 million (was 105 million) Xbox Series S/X: 48 million (was 60 million, then 67 million, then 57 million)
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima
