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It's just a weaker Series X and it seems to be fundamentally the same platform. So the sales ought to be lumped together.
Changing, companies, let's say Nintendo had 2 SKUs at launch for the Switch's successor. One was right around Xbox One performance, or slightly weaker. And then one was super powerful for a hybrid with roughly PS4 Pro specs. They would still be fundamentally the same platform. Both would be replacements for the Switch and have an identical (or 95% identical) library.
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
