Sure, the Switch can do it, I just don't think it will. Think 2020 is the peak year, it'll still be going strong next year, and then sales will start declining fast, but maybe I'm wrong in thinking that. It just seems to be the rule for Nintendo home consoles, but yeah, the Switch isn't really that. Kinda get the feeling that we'll get another Mario, BotW 2, and after those two we're not gonna get more major hardware-moving games.
I'm also thinking the PS5 will have a slow start, meaning the PS4 will continue to sell well for at least another year or two.
PS4 realistically will stop at 125 million, with 130 million being in my opinion the best case scenario. i don't know what you mean with "low start", but i think you severely underestimate next gen consoles. PS5 launch is going to be huge, Sony already confirmed pre orders are higher than PS4, and Sony plan to ship (so sell) more units than PS4 at launch. If anything, i agree PS5 lifetime won't beat PS4 but at launch it'll be bigger.
But anyway, 125 or 130 million for PS4 isn't that important, i think we all agree this is gonna be the range.
Now, for Switch, look at this:
2020 - 28 million / 80 million
2021 - 20 million / 100 million (-30%)
2022 - 12 million / 112 million (-40%)
2023 - 6 million / 118 million (-50%) <--- Switch 2 in November
Lifetime - 120 million
You see how pessimist (and unrealistic i would say) i went with those estimate, yet it still reach 120 million so easy?
Keep in mind 2020 line up, outside of Animal Crossing, was absolutely shit, and for the next years we have at least one new model (probabily more), and they still have to make a pricedrop.
And 2020 had shortages for all year.......
There is absolutely nothing that suggest Switch to drop like this. "could happen because Switch is an unprecedented situation" is not a reason.
Oh yeah, of course, November 2023 seem early, not impossible at all but considering how many times Nintendo said Switch is barely in the half of his lifecycle, 2024 seem more likely for Switch 2.
Imo, Switch will beat PS4 by a huge margin.