So, I decided to mess around with a bunch of spreadsheets to answer this question:
What if the Switch has the exact same sales curves as previous Nintendo consoles?
I got these numbers by comparing Nintendo's prediction of the Switch's first year (10 million units) to the first years of every other Nintendo console. Then, I multiplied the rest of the years by that ratio. FY3/2017 is always 2.74 million and FY3/2018 is always 10 million. Everything is presented from worst to best-case scenario.
Lifetime sales: 31.04 million
Ah, the poor Nintendo 64. It was so front-loaded. Its first year was its peak, and then it was all over.
Lifetime sales: 33.89 million
Nintendo 64: The sequel.
Lifetime sales: 39.95 million
The Wii U was killed prematurely because it was selling like 3 million a year. Would Nintendo kill the Switch off after three consecutive years of sales between 10 and 13 million? Probably not.
Sales as of March 2024: 48.94 million
The 3DS is still going, so we could safely add another 5-10 million for lifetime sales in this model. The 3DS has this weird pattern where it sold a stable 13-14 million per year for three years, and then it moved down and started selling a stable 6-7 million per year. Not good for the Switch, which is forecasted to have a first year that's 26% lower.
Lifetime sales: 49.81 million
The Game Boy Advance basically reached peak sales immediately and then kept the exact same pace for four years. Similar to the Wii U in a way, although the GBA actually had a decent tail. Wouldn't be great for the Switch, though, since it would be selling around 9 and 10 million per year instead of 15 to 18.
Lifetime sales: 54.21 million
The Wii had the absolute best first year of any Nintendo console, giving the Switch its worst ratio in this comparison. Still, the Wii was a monster with a 26 million peak, which is why this sales curve ends up higher than the N64, GCN, GBA, and possibly 3DS anyway.
Lifetime sales: 75.26 million
The SNES had a pretty good tail, and that 98% YoY increase after the first year doesn't hurt either. Probably the most realistic lifetime figure, considering the gap between this and the next projection.
Lifetime sales: 132.54 million
The first year of the DS wasn't all that impressive: Just 11.46 million, lower than the GBA, Wii, and even 3DS. But then it had four consecutive years above 23 million and a peak of 31 million.
Lifetime sales: 149.66 million
Can we safely say that the Game Boy had the absolute weirdest sales curve of any video game console? Sales rose every year from its 5th year onward and it peaked in its 12th year, two years before being discontinued. I don't really see this happening to the Switch, unless 1) Nintendo just keeps making revisions and lumping it all together under the Switch brand and 2) something new and as explosively popular as Pokémon is released around 2026.
Side note: I cheated here by starting from the Game Boy's second year instead of its first year, since it hadn't even launched yet outside of North America and Japan at that point. Had I used its first year, (2.84 million), it would have put the Switch's lifetime sales at 429.71 million, with a peak of 66 million.
I didn't do the NES for three reasons:
1) We don't have separate data for its first three years in Japan.
2) Nintendo used different fiscal years (ending in August instead of March) until 1989, making it confusing to compare.
3) The NES sold so little in its first year in every market that we would get something like 200+ million anyway.
