Nintendo themselves said they wouldn't be able to produce as much as they wanted. That said the shortages have already been a problem for Nintendo last year and they still moved like 25mil consoles. The Switch is less affected by the shortages than the other consoles. This year the shortages will loosen too, so they will definitely be able to produce more than what you say.

Was Switch ever sold out 2021 holiday?

I voted 20-21.9 mil. Software lineup of major first party games is gonna be insane but I think we'll also see Switch saturation starting to take effect so huge software sales but those games will have less of an impact on weekly hardware sales. I'd guess 21.5 million, putting it at about 124mil total.

I'm gonna go higher than most and predict 24-25.9m (in the lower end though)

Of course that's assuming they can actually ship that much and it might require a price-cut. We'll see, maybe things won't work out that way.

Voted 24.0 - 25.9 million

I expect 2021 to be around 25M, so next year either slightly up, flat or slightly down  

This mainly depends on WoM for three key titles. If WoM for all three is great than I can see Switch being up YoY. 

Arceus ensures the year starts strong and generates post-holiday hardware demand, on-going DLCs and Expansions ensure it continues to chug along through-out the year and despite opening lower it overtakes Brilliant Diamond/Shining Pearl's lifetime sales by the end of 2022 and becomes the 2nd best selling Pokemon game on the Switch behind Sword/Shield. 

Splatoon 3 is the huge software seller in Japan and East Asia for the summer months and due to it's on-going support has an exceptionally strong holiday Quarter, Splatoon 3's 2022 is so big it's comparable to New Horizon's 2020 in software sales but isn't able to match the hardware momentum New Horizon & COVID created in 2020. Its not as big in the West but sees considerable growth and surpasses Splatoon 2's LTD sales by the end of the year(if it launches before September)

Breath of the Wild sequel generates huge demand for hardware in the West in the fall, offsetting some of the declines we might see in Europe and North America through-out the year. It's the biggest launch for any Switch title with over 17 million sales in its launch quarter. Its also the first Zelda entry to launch with over 1 million physical sales in Japan

Beyond these three huge titles there is a huge number of other titles that will help momentum both from Nintendo and third parties that ensure a very lively ecosystem with a lot of competition. 

This will be another fun thread to look in a year. Guessing 22-23M

20 million.

Bonus question: Triangle Strategy, closely followed by Pokémon Legends: Arceus.

24-25.9 million.
Switch demand will pretty much stay the same as last year.

Oh so it was Nintendo themselves. I couldn't remember where I read it at. You said they moved 25 mil consoles?! Eh...you sure? That's a lot. If so, then that's super impressive and more than any console sold in a year in recent memory.

If the console shortage let's up, then I will adjust my prediction to 21 mil. Switch is certainly capable. I have 5 Switches in my household. We have certainly contributed to that rising number.

Voted for 20 - 21.9m. More specifically I expect around 20.5m.

Bonus question: Breath of the Wild 2, obviously.