Hmm. I do think the sales will be pretty front-heavy for the launch and first year. But I think it will have some legs.
Pessimistic: 25 million
Optimistic: 35 million
Let's meet in the middle at about 30 million. Breath of the Wild has already exceeded 30 million, and still a little juice left in it.
Lifetime Sales Predictions
Switch: 161 million (was 73 million, then 96 million, then 113 million, then 125 million, then 144 million, then 151 million, then 156 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