This won't even be close. A better question is who will win 2021 between Switch and PS5+XBSeries. Switch could be mid 20 millions, PS5 will probabaly be mid teens, and Xbox will probably be under 10, so the latter two combined should be close to Switch sales.
Yeah. From the other similar thread:
Here are the combined yearly sales of the PS3/360 and the XBO/PS4. Using VGC Data, figures rounded to thousands.
Switch tops the Gen 7 combined peak if it passes 28.4M sold this year (needs to sell 8.6M in the final 7 weeks of the year - it did 8.1M last year so this should be easy).
Switch tops the Gen 8 combined peak if its passes 27.4M sold this year (needs to sell 7.6M in the final 7 weeks of the year - it will be close to this by Cyber Monday IMO).
How about straight up best years of Gen 7 and Gen 8 consoles, without lining up the years? Gen 7 stays the same (2011 for both). Gen 8 goes up to 28.2M (PS4 2017 + XBO 2015). So the story doesn't change.
Point is, 2020 NSW is on pace to pass the combined best year of sales of both 360/PS3 and XBO/PS4. That's with supply/production issues hitting the entire industry (RTX 30 series, Ryzen 5000 series, upcoming RDNA series, NSW, PS5/XBS - everything is struggling to meet demand right now). IMO if Nintendo could have produced/shipped 35-37M NSW consoles this year, they would have. Yet they are likely only going to sell/ship 28-32M this year and this FY.
Those problems are not going to go away come January. Nothing magical is going to happen with PS5/XBS that's going to boost them past the performance of the previous 2 gens (save for Series S price point of $300 - we will have to see how that penetrates the market, especially outside of the US). Reasonable expectation though, is that the combined sales of both Gen 9 consoles should hit 27-29M some time in the Y3-Y5 range (counting 2020 as Y0). NSW I am certain will stay above 30M in 2021, and at the very least should hold the fort above/around 25M in 2022 (we will have to wait and see how Nintendo's hardware strategy plays out regarding Pro vs. Switch 2).
So I think this thread/prediction is too conservative. The Switch should hold up well vs both XB/PS combined in the next 2-3 years. PS5 alone is too easy of a target (especially at $500 price point, especially with Sony not supplying a heavy share of the $400 SKU).