If you count the Switch as eighth generation, you're probably right. Nintendo does cut their hardware off like crazy, even the mega hits. But even then, I see the appeal of the Switch as a budget platform once Switch 2 is out.
I don't count Switch as 8th gen, so I would say the PS4 will be the most successful. Xbox One will probably barely creep to 50 million units. There's only one SKU of it left at this point. I think the PS4 can hit 120 mil on the low end, and 130 mil if Sony is very assertive with it.
Lifetime Sales Predictions
Switch: 151 million (was 73, then 96, then 113 million, then 125 million, then 144 million)
PS5: 115 million (was 105 million) Xbox Series S/X: 57 million (was 60 million, then 67 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
