Yeah, 80m is like bare minimum that Switch will do LT, I mean it will be at around 35m+ just after two first years on market.

Yes, but let's wait to see the impact of PS5 and Xbox Next on Switch sales. The sales could get lower faster than usual once it appears like "older gen".

And let's not forget than even the Wii had an intense but short life. I'm curious about how long the Switch will live before we talk about the next one. 

I think the switch market is the 3ds market. When the next gen consoles arrive, the quality and production disparity of games will be absurd and the switch should be discontinued for an eventual switch 2.

Dont mind this.

Switch has this in the bag. 80 million is pretty much a lock.

If PS5/XB2 are not some kind of hybrids of handhelds, I dont see they will have any bigger effect on Switch sales. Despite PS5/XB2, Switch still be hybrid/handheld and not direct competition to PS5/XB2 in any case, similar like we seeing now with PS4/XB1 compared to Switch sales.

Switch is not Wii and Nintendo is not same company from Wii period. First Switch is on first place handheld hadware that acts like handheld/home console hybrid while Wii was just home console, so Switch will similar to 3DS have multiply revisions and price point offers, while Wii had only one revision at end of Wii life. Second, Switch is Nintendo's unified platform, that means all Nintendo IPs (both home console and handheld ones) on one platform, and that means strong support. Third, Switch is becoming Nintendos only platform so they will be much more cautious with planning and supporting it compared to Wii, they itself said they planing for Switch to have longer life span than around 6 years.

it's looking likely that switch will pass it, but you never know.

Sure, all your arguments are valid. But in my opinion, there are still several unknown factors. Even if the new other consoles are not direct competitors, the "new thing" factor will definitely overshadow the Switch, and all the PR and articles will focus on the new gen. The image of the Switch could be damaged because it will still be considered "previous gen" (and kids, for example, might want "the new one" instead of the Switch now). And yes, it's a handheld, but let's not forget that the handheld market is shrinking more and more every year since the DS/PSP days, so we still have not idea what the size of this market is at the moment, and no idea about when it will be close to saturation. The Switch could do something awesome and make it grow again, but I wouldn't count on it too much, it would be a (good) surprise. 

I'm not saying "the Switch will fail", far from it (I will surely get a Switch for Christmas anyway). Just saying that the Switch is in a new position compared to the usual models, and we don't know yet the limits and how it's going to evolve with new external factors. So I'm just curious to see what will happen. Could be great, could be less great, but in any case it will be interesting to observe. 

Not only will the Switch pass it (unless sales somehow fall off a cliff), but I think the 3DS has a shot to pass the mark also. It currently sits at 73 million and only needs another 8 million to do it. I realize that the 3DS is near the end of its life and Nintendo is putting resources towards the Switch, but so long as they continue to produce units and give it at least second tier support it could last just long enough. Sony abandoned the PS Vita years ago and it still managed to sell almost 20% of its final total in those twilight years (~3 million sold 2016-2018 out of 16 million total).

Just as psychicscubadiver stated, not only do I think the Switch will beat the PSP, but the 3DS also has a chance for depending on how much longer Nintendo supports it. At the conclusion of the year, the 3DS should be somewhere between 74-75 million units sold and between 75-76 million units shipped.
The last shipment number I heard of for the PSP was 82 million. https://m.ign.com/articles/2014/11/17/vita-sales-are-picking-up-thanks-to-ps4-remote-play
“82 million PSPs in the wild” can be taken many as either shipped or sold. That is some odd phrasing, but dor now I’ll say it’s shipped and the 80.8 million VGC has is sold.
That would mean the 3DS would have between 6-7 million million units left to ship and sell to catch it.
Difficult, even unlikely, but it’s not impossible.