Don't see it happening. It can get 30m+ but won't beat GB/DS. Switch's time is almost done.

I think the successor to the Switch is going to release in 2024. So yes, for me there's no way the Switch doesn't top the DS in Japan.

No I don’t think it will. It needs another 12M, and I don’t think it has the years left to do it. It would take roughly three more years. Also Japan pretty much has a hard limit on how many people can buy a video game system; and that limit isn’t growing.

Worldwide NSW is around 13m shipments behind NDS launched aligned (89m v 102m) and it will fall further behind with thursdays Q2 sales report but it can still beat it by having a stronger tail. I think NSW will beat NDS in Japan by being stronger in it's final years.

So, I looked at the numbers, and Switch might surpass PS2 at the end of the year or if not early in 2022. 3DS will follow throughout 2022. So reaching #3 is inevitable at this point. Reaching GB and DS numbers through is a tall order. If Switch maintains near peak numbers throughout 2022 and the successor doesn't come too soon, it might have a chance.

You can pretty much copy and paste what Rol said onto my post. Because that's what I was going to say almost note for note.

The Switch, while past its peak after this year, still has A LOT of gas left in the tank. As evidenced by what Nintendo has planned so far for next year.
In 2022, we'll have Pokemon Legends: Arceus, Splatoon 3, Bayonetta 3, Kirby and the Forgotten Land, and Breath of the Wild 2. Then, for 3rd parties we've got Triangle Strategy and Monster Hunter Rise: Sunbreak. Now that we're in Year 5, approaching Year 6, of the Switch, all of the 3rd parties who realized by Year 2 that the Switch was going to be a big success and started rapidly scrambling to develop their games for it, have started to show the fruits of their labor and that's going to continue well into next year.

Plus, there's going to be some more Nintendo 1st party stuff that they haven't announced yet. We're due for new Fire Emblem, DKC, and Yoshi games. We're also due for a new game from Monolith Soft, whether it's Xenoblade 3 or a new IP entirely. We're due for the next 3D Mario game after Odyssey, since it has now been 4 years since that game came out. Also Pokemon Gen 9 is going to happen at some point, if not next year than the year after that. And last but not least, Metroid Prime 4 - which is looking more and more likely to be the Switch's swan song, whenever that game is released.

The Switch's library, as impressive as it is now, is only going to get higher and higher. With all that going for it, I would be shocked if a Switch successor gets released at any point sooner than Spring 2024. Because that would mark 7 years since the Switch came out, and if the PS3, PS4, and Xbox One could each get 7 year cycles, the 360 even got an 8 year cycle, before their successors came out, why can't the same be true for Switch? Especially now that this will more than likely be Nintendo's only line of hardware moving forward and the consequences for a mistimed launch this time around are FAR steeper than they would have been if they maintained their separate console and handheld divisions. Because back then, if they botched the launch of their console, they at least had their handheld to fall back on. But now? If they botch the launch of Switch 2 by releasing it too soon and/or not having a strong launch lineup for it, they're in trouble.

These big EPD releases in 2022 are a good point, haven't thought about it, but a Switch 2 in 2023 would go nearly empty on new big releases, as the studios aren't ready again.

I expect that Switch sells 6M this year and reaches 23M at the end of this year.

2022: 4M = 27M total
2023: 2M = 29M total
2024: 1M = 30M total
2025 until end of life: 1M = 31M total

If the OLED model has a strong momentum and Switch sells 5M next year, then it should be able to come close to GB/DS.

1. Yes, Switch will take the #1 spot in Japan.  

2. As several others have said, there is basically no chance of Switch's successor launching in 2023.  You can always tell when Nintendo is going to launch a new system, because the big first party titles stop getting released.  Usually, first party support is like one big title and a few small titles and that is the best case for the year before the successor system.  (The Wii didn't even get that.)  The 3DS had Pokemon Sun/Moon as it's only big title in 2016.  That is typical the year before a successor.  The NES had Super Mario Bros 3 a year before the SNES released, but that was it's only big gun, and they were releasing far, far more first party titles when the NES was a new system.  Nintendo first party releases dry up a year or more before it releases a successor, and it has been that way since the beginning.

Switch is getting at least 3 big guns in 2022 (Pokemon Arceus, BotW 2, Splatoon 3) and several smaller titles (Advance Wars, Kirby, Bayonetta, etc...).  That is a lot of first party games.  If Switch 2 were about to be released, then these games would be developed for the next system instead.  Don't count on that successor console coming anytime soon.  

There is also this misconception that releasing a new system causes hardware sales to drop off a cliff.  That is not exactly right.  It is more accurate to say that hardware sales drop when Nintendo's first party releases drop off too.  When Nintendo releases big titles, then it gets big hardware sales.  When it releases almost only small titles, then it gets small hardware sales.  And when they even stop releasing small titles, then they get no hardware sales.  Their consoles live and die off of first party software. 

There are too many big titles coming for Switch to die off any time soon.  There are several more years of good sales left in the Switch.

About 10 million to go after end of this year? Seems doable.

Sales should start falling next year a bit, but I doubt it'll be a drastic fall from the ~6 million of these two years. I could see it knock out 8+ million in '22 and '23. Assume a spring '24 successor launch (doubt it would be any earlier than that) means by launch of successor it'd maybe be 1.5 million or less to go. I think with a Spring '24 successor launch Switch will just barely eek by DS, but will easily pass it if a holiday '24 Switch 2 launch happens.