Three majors factors and one minor.

1)3d free glass technology. Nintendo has polícy games for everyone, what happens when launched a platform with 3d free glass exclude children and people don't like 3d free glass? And all the games have brought this feature, the arcade roots( Nintendo roots) go against the 3ds directions, Nintendo loses more potential market.

2) The Price, portables so far is more affordable than a stationary videogame. GB, GBA, DS all have a low price point.

3) The casualization of touch generation. The DS core, touch generation, go to shovelware and bad games, try to copy Nintendo games. But Nintendo really invests the A team with good money on the projects, most thirds don't go this way. The new market, touch generation, go away with crappy games and abandoned this try indeed with Nintendo.  And the occidental support migrates to Smartphones mythos heaven.

4) Smartphone multimedia better device than a portable videogame. This one hits more sony than Nintendo. But hits Nintendo in some way too.

There's only three possible explanations for the Switch selling what it has over the past year:

1) The pandemic causing an increase in demand for at-home entertainment, including video games.

2) Residual effects from Animal Crossing.

3) Natural increase in demand.

I believe #1 is the only explanation that conforms to the available body of evidence. It explains the increase in demand not just for the Switch but for the PS4 & XBO as well. The other explanations simply aren't adequate, for reasons I spend countless hours explaining. When evidence was offered to back up those explanations, said evidence was either inapplicable or actually didn't prove anything. Nobody thought the Switch was going to sell anywhere close to what it did in 2020. Even the most optimistic predictions fell way short. Now some are pretending that the Switch would have sold what it did even if there had been no pandemic, despite every reason to believe the contrary. Even if we were to agree that the pandemic is not currently driving the high sales we see, that momentum would not have existed in the first place had the pandemic not been a thing. The COVID bump at minimum was a factor for a good number of months and opened the floodgates.

That's my position and I'm sticking to it until a better explanation emerges.

If some people don't agree with that, fine. I don't expect to be able to convince everyone. But I can't even mention the COVID bump without everyone dog-piling on me as if I had made the most preposterous claim since "the world is flat." I think a lot of this goes beyond simple disagreement, and that some people are taking it personally, as if I'm somehow diminishing the Switch's success or something. Regardless of the reasons, I'm tired of people jumping on my case and implicitly demanding I spend hours reiterating the same points I've made since last summer. We've been going around in circles for many months now.

It ends now.

I don't want anyone asking, inquiring, replying, or otherwise directly pestering me on the subject anymore. If people want to argue about something other than the pandemic's effects on sales, fine, but I don't want anyone arguing with me over the subject anymore. Not a one of us has anything new to add to the discussion, and so we're just wasting each other's time at this point.

Are we clear?

There's only three possible explanations for the Switch selling what it has over the past year:

1) The pandemic causing an increase in demand for at-home entertainment, including video games.

2) Residual effects from Animal Crossing.

3) Natural increase in demand.

I believe #1 is the only explanation that conforms to the available body of evidence. It explains the increase in demand not just for the Switch but for the PS4 & XBO as well. The other explanations simply aren't adequate, for reasons I spend countless hours explaining. When evidence was offered to back up those explanations, said evidence was either inapplicable or actually didn't prove anything. Nobody thought the Switch was going to sell anywhere close to what it did in 2020. Even the most optimistic predictions fell way short. Now some are pretending that the Switch would have sold what it did even if there had been no pandemic, despite every reason to believe the contrary. Even if we were to agree that the pandemic is not currently driving the high sales we see, that momentum would not have existed in the first place had the pandemic not been a thing. The COVID bump at minimum was a factor for a good number of months and opened the floodgates.

That's my position and I'm sticking to it until a better explanation emerges.

If some people don't agree with that, fine. I don't expect to be able to convince everyone. But I can't even mention the COVID bump without everyone dog-piling on me as if I had made the most preposterous claim since "the world is flat." I think a lot of this goes beyond simple disagreement, and that some people are taking it personally, as if I'm somehow diminishing the Switch's success or something. Regardless of the reasons, I'm tired of people jumping on my case and implicitly demanding I spend hours reiterating the same points I've made since last summer. We've been going around in circles for many months now.

It ends now.

I don't want anyone asking, inquiring, replying, or otherwise directly pestering me on the subject anymore. If people want to argue about something other than the pandemic's effects on sales, fine, but I don't want anyone arguing with me over the subject anymore. Not a one of us has anything new to add to the discussion, and so we're just wasting each other's time at this point.

Are we clear?

Nintendo didn't turn off consumers cause the 3DS had 3D, if people didn't want to play in 3D they could easily turn the slider down to 2D and games were still more than playable in 2D.I never hear anyone say they won't purchase a 3DS because they don't like 3D.

While I agree that 3D wasn't an impressive enough gimmick to draw in the same crowd as the DS or Wii did, to say that people didn't buy it cause they hate 3D is illogical, a better reason is to say they didn't care enough about 3D tech.

Plus most Nintendo handhelds after the July 2011 3DS price cut were around the same price and in a lot of cases even more than the 3DS which was 170$ in July 2011 when you account for inflation.

Here is how much each Nintendo handheld at launch would cost in 2021 when adjusted for inflation:

Gameboy: 190$

GBA: 150$

DS: 210$

3DS: 200$ (July 2011 and beyond)

This shows the 3DS's price wasn't the problem for the 3DS, the DS sold twice as much as the 3DS at a slightly more expensive price point and the GB and GBA were close to the 3DS's price as well.

Your last 2 points are the primary reason why the 3DS didn't sell as well as the DS.

What makes Switch especially hard to predict in my view is the uncertainty regarding the length of its lifespan. Nintendo are very inconsistent when it comes to how long they support their systems for.

For this reason, while 140-150 million seems most likely to me, it's hard to nail down when I can see it being replaced anywhere from 2022 to 2024.

What makes Switch especially hard to predict in my view is the uncertainty regarding the length of its lifespan. Nintendo are very inconsistent when it comes to how long they support their systems for.

For this reason, while 140-150 million seems most likely to me, it's hard to nail down when I can see it being replaced anywhere from 2022 to 2024.

You can see it be replaced next year? The year that Splatoon 3 and Pokèmon Legends Arceus release, right after the consoles peak? That doesn't make sense. Also they made it clear several times last year, that the Switch will have a longer than usual life, so 7-8 years is what I expect, so replaced in 2024-2025. 2022 doesn't make any sense and even 2023 would be to early go against everything they said and did thus far, like announcing Splatoon 3 for 2022.