Ahh ok, Astral chains does look interesting. Also yes that is very true, it wasnt a bad game, just abit niche.

1) New Switch Model for 299$/€
2) Price Cut in OG and Lite models (ideally, to 199$/€ and 99$/€, respectively).
3) The following games launched on 2021 and 2022: Breath of the Wild Sequel, Next Metroid Prime, Super Mario Oddysey 2, Super Mario Galaxy 2 HD, New Tomodachi Life. New Pokemon Mainline Game(S). And, ideally, GTA V Switch Edition and some other big 3rd party games (Like Dark Souls 2 & 3,RDR, etc.). Leave everything else (New The Legend of Zelda, new 3D Mario, new 2D Mario, New Mario Kart, etc.) for Switch succesor.

With these 3 (plus, as said, not letting it die too soon by stopping support), it would be easy to reach 150m.

To the OP's points,

1) yes they should do more casual games of course. Turn Ring Fit into a series of several games to give those millions of Ring Fit players more fitness games to play and be able to market Switch as something with a full fitness lineup of games. Also obviously they should bring back the hugely popular Wii Sports. Port over Wii Sports Club from Wii U and add in Wii Sports Resort to it as well as an ultimate Wii Spots online combo. Bring back other casual games like Nintendogs and more that found success on the DS.

2) More hardware models for sure. But they've already apparently got an upgraded model coming next year. Assuming that is an upgraded hybrid model then I'd say the only thing they should add on later to the Switch family is a Switch Home for those people who want the premium experience the upgraded model has but don't care about portable play and want it cheaper.

3) Definitely Nintendo needs to keep pushing into new regions. They should be marketing the hell out of the Switch to try to get more sales in eastern europe where I guess Sony just completely dominates, though I guess a big part of that would be getting better soccer games on Switch. And of course push further into other regions as well.

4) The 3rd party output is getting better and better every year so I think this is already handled. Nintendo is probably never going to get a full slate of new AAA 3rd party games because 3rd parties just prefer to market games with the flashiest graphics so that means they will always go to the most powerful consoles, but 3rd parties are starting to come in pretty strong for Switch now so I'd say this is already solved.

What I'd say the need is:

Hardware: Switch Premium/Pro/whatever at $300 early next year, drop OG Switch to $250, add Switch Home at $200 maybe early 2022, and then early 2023 cut the price of everything to keep it real competitive as it starts getting late in Switch's lifecycle, and maybe just drop the OG model at that point. Have Lite/Home/Premium drop to $150/$170/$230 at that point.

Services: Add GB, GBA, and N64 to the Switch Online service. Make Switch more online-play friendly by allowing voice chat over the system itself instead of the bizarre mobile app thing, and finally get rid of friend codes so its easy to actually connect with people online, and allow messaging through the system as well so you can actually send your friends a message on the Switch about jumping into an online game. All this would just make Switch a more much serious system for online play, which a lot of people are interested in.

Software: Just pump out loads of great software. There are tons of Nintendo properties left to be put on Switch, and first new versions of Nintendo properties to put on Switch, and plenty of sequels games that could go on Switch. Jam pack next year full of great games like Mario 3D World, a Zelda Collection, BotW2, some sort of Pokemon game, Metroid Prime Trilogy, Wii Sports Online compilation, new Ring Fit, 2D Mario, Bayonetta 3, and more. Then continue packing the library with Nintendo IP in 2022 and 2023. In general, put out more big name casual games like Ring Fit, Wii Sports, Nintendogs, etc. Stop making mistakes like releasing Pikmin 3 Deluxe instead of a Pikmin Trilogy, leaving out Galaxy 2 from Mario 3D All-Stars, or releasing Mario 35 for only 6 months instead of allowing it to permanently add to the value of Switch Online. Embrace Nintendo's portables series like Golden Sun, Advance Wars, Mario & Luigi, WarioWare, etc and do portable-style version of Nintendo IP, like do a new 2D Zelda game, a new 2D Metroid - do smaller, cheaper, (and I'd say make them more experimental too) versions of big Nintendo franchises as kind of keeping that secondary line of games alive in the time of only one Nintendo system. Bring back abandoned series or put new effort into revitalizing waning series, like Fzero, Star Fox, and more. Bring out new versions of games that have so far only got a port, the start of a fresh Donkey Kong platformer series, the start of a fresh 2D Mario series, Pikmin 4, get Metroid Prime 4 out, maybe not Mario Kart 9 but something similar to Mario Kart like a Nintendo Racing Smash-style mashup game that has enough differentiation from Mario Kart like N64 had back with MK64 and DKR. Also sequels to major games like one more 3D Mario, perhaps a Pokemon remake and then a new generation later on (and apparently they are already making some sort of Pokemon collection of ports as well), a successor to Mario+Rabbids. Basically just pump out a ton of great Nintendo games for years to come. This could extend the life of the Switch before being replaced all the way to holiday 2024 or early 2025. Also start up the Nintendo Select's discounted games soon on Switch so people can get a variety of first party games at $30, some obvious games whose sales have slowed down and would benefit would be Arms, Splatoon, Mario Maker, Odyssey, Link's Awakening, Let's Go, DKC:TF, and several others. Also talk to 3rd parties about being competitive with game pricing - stuff like Witcher 3 and Elder Scrolls should not cost $60, old 3rd party ports should drop in price pretty quickly to match what they are on other systems.

First, they need enough stock. 2021 should have equal numbers like this year. I expect a Switch XL coming next year. That should help to hold high hardware sales together with ongoing pandemic.

In 2022 we need a price cut. Switch Lite should then be 150 $. In 2023 and until end of life Switch Lite should be 99 $. In 2024 we should see a successor. If a successor already comes in 2023, it's unclear if Switch can reach 150M.

Wait, how is it on track to sell 160-170 million?

I thought it was more like 120-135 million?

How is it on track to sell 120-135 million?

Price cuts, and becoming mainstream in china.

Continue making even more ports and remakes should do the trick.

Close future is pretty easy, unless they are struggling to make stock they will sell 27+ million this year... for a LTD of 76mln.

If this year is the peak and it has similar yearly drops as the Wii did after it's peak then it will end at around 140mln... but as it's peak is later in life by 1-2 years it could fall a little faster than the Wii.... 120-135 million isn't unreasonable to me.

I mean it's still trailing behind the DS launch aligned, selling a similar monthly amount even with the pandemic boost, and DS topped out at 155million. Not to say 160 million isn't possible, if it can keep momentum going through next year (for example if large swathes of society are still being quarantined or working from home) then that's a good range.

I think the real question is, SHOULD the Switch reach 150M sold? Meaning, is it in the best interest of Nintendo to sell that many? Fact is, the only two consoles that reached 150M units sold were succeeded by the worst selling items for that company in those categories. The PS3 is the worst selling Sony home console, and the 3DS is the worst selling Nintendo portable. Perhaps Nintendo should focus on continuity of the brand instead, and not focus so much extending the life of the Switch that the successor suffers as a result. It's probably better if they sell 130M Switches and 100M+ Switch 2s, than 150M Switches and 75M or fewer Switch 2's.