http://garaph.info/static/shipments/3DS_WW.html

3DS (early 2011) peaked at 15.51m from October 2011 to September 2012. If you specifically want peak CY it's 2011 at 15.03m and peak FY was 2012 at 13.96m.
Wii (late 2006) peak was FY 2008 at 25.94m
NDS (late 2004) peak was CY 2008 at 31.43m

Switch (early 2017) did 26.63m from October 2019 to September 2020, this will keep increasing for at least the next 2 quarters.

Is this a new meme that I'm not aware of?

PS4 sold 8.4M last year. It needs to sell 5.2M to reach 120M. Which doesn't sound like much, but considering how the sales have been in freefall throughout fall, I really doubt it can sell more than 3M this year and 5M total from this year on.

No... at least not yet!

No, just the same old song and dance we've been hearing since 2017. Comparing the Switch to the Wii is especially foolish now that the two are so clearly completely different in terms of their circumstances and sales trajectory.

I picked second half of 2022 (so basically end of next year). I could see the Switch selling about 23 million units in 2021 and about 17 million in 2022. On top of being likely around 80 million by the end of 2020, this means Switch sales would be around 120 million at the end of 2022. At worst, I could see the Switch being only a couple million behind the PS4 by that point, assuming the Switch sells like I'm predicting it will this year and next year.

Was supposed to be a 7, not a 4, my bad (it's 8.753M to be exact)

Sales for the PS4 have completely broken away. They already started doing so during summer where the weekly sales numbers slowly creeped down to below 100k, and during the holiday season the best-selling week didn't even manage to get past 200k anymore. In fact, December sales were only on par with those of January last year.

I expect the console to continue it's trend and weekly PS4 to go down to Wii U levels pretty quickly, and then drop even further in fall. So yeah, 2.5-3M is about what to expect from the PS4 imo.

More like 2002. It's been the same song and dance since I created my VGChartz account in 2007. It's a perpetual cycle where the same arguments are being repeated again and again.

Nintendo console sells bad (GC, Wii U): "Nintendo consoles don't sell. Nintendo should go 3rd party."

Nintendo console sells good or great but not as well as Sony's console (Wii in its later stages, 3DS, Switch at first): "Sony consoles always outsell Nintendo consoles. Wii / DS don't count. Nintendo does not have the third party support to achieve high sales. They lack AAA western third party games."

Nintendo console flat out smashes sales records and leaves the competition in the dust for a brief period of time (Wii, Switch before the 2020 sales explosion): "Sales are going to fall off a cliff! Nintendo consoles can't sell well for a prolonged period of time. Nintendo consoles only sell because of a gimmick, the novelty will wear off soon. The console is not powerful enough to sell well for more than a few years."

Nintendo console doesn't stop smashing sales records (DS, Switch): "It doesn't count! Only Nintendo games sell on Nintendo consoles, so it still doesn't count. Handhelds don't count, they always sell well (*), we should focus on the home console market."

(*) This argument died with the Switch because with the Switch the narrative turned into "handheld gaming is dead".

Of course, third party games sell great on the Switch and sold great on Wii and DS, so the last point turns into a heated debate as this is the last resort. It truly is a never-ending cycle where no matter what Nintendo does, or how well a Nintendo console sells, there's always the same arguments against them. And this has been the case since the Gamecube days when Internet forums become more and more popular.

This also happens every single time:

Before: Oh noes, third-party games suck, they are all for dudebros and bakas!
Now: OMG, third-party is the greatest thing ever!

Show me a single post of that happening

I agree with both of you. Sales are going to fall off quick. That being said...I do think that the PS4 will pull off 3M minimum this year. There is a chance for it to hit 120M, but it will be a snails race. The kind that we saw recently with the 3DS and the PSP. It looked like 3DS might pull it off...then sales just weren't there. Might be the same thing with the PS4. Either way...it's definitely not as sure of a thing as I thought in 2019.