I am doing a proper analysis that isn't limited to the eighth generation. Of course that puts me at odds with all the people who do not look at the big picture or don't even want to do that. I've already made my own thread to address common fallacies when it comes to Switch predictions.

The fallacy found in your post is that you assume a short lifecycle which is usually based on processing power, but that has no basis in reality. The 3DS lasted six years before its successor launched, the same holds true for the DS. The Gameboy lasted even longer. The only exception to the long lifespans of portable Nintendo hardware is the GBA, but that was triggered by Sony entering the handheld market and Nintendo wanting to avoid a scenario like in the home console market where it took them over 18 months to put out a competitor to the PS1. So logically, the only things that can lead to a short lifecycle for Switch are either incredible stupidity on Nintendo's part by trying to kill Switch off prematurely, or a serious challenger entering the arena. But considering that Nintendo comfortably beat everyone in the handheld market, including PlayStation, that's not a likely scenario.

Here's a breakdown by year that starts with my original prediction for 2017:

2017 - 8m
2018 - 16m
2019 - 22m (Revision, price cut and full understanding of the market that Switch is a successor to both Wii U and 3DS)
2020 - 21m
2021 - 20m
2022 - 15m

There are going to be more sales beyond 2022, but 100m are already reached with the above. The peak years are going to be quite flat, but that's in line with previous systems that got properly supported. The dropoff in 2022 is explained by Nintendo's top development teams preparing for the launch of a successor in 2023, so the first party lineup won't be as high profile as in previous years.

Switch is going to peak higher than the PS4, because as a gaming device it's not only more forward-thinking, its software lineup is also going to appeal to more demographics. Of course it's very much possible that the hybrid concept gets embraced by the market within 2017 which would result in a better first year. But right now it isn't crystal clear yet that Switch will get all the handheld support from both Nintendo and third parties, plus the hardware price in many countries is less than ideal (for example, €299 sounds a lot better than the actual €329), so I don't expect Switch to be beasting throughout its first year on the market.

People cannot imagine the Switch selling more units lifetime than the PS4 because they believe that the PS4 is doing amazing and because they tend to attribute any Nintendo success to luck despite Nintendo being the only company who can boast with a clean streak of domination. The PS4 isn't doing amazing. It benefits from the lack of noteworthy competition and being available in more countries than any other console. This global availability masks the merely decent sales in the USA and Japan, but it's clear that the PS4 is not selling like the PS2 and only looks as good as it does because it pushes the backend sales of the PS2 to the frontend. The PS3 couldn't get backend sales like the PS2 either, also because it launched in more countries sooner.

The biggest mistake people make when analyzing the Switch? They separate it into home console and handheld, and look at these parts individually to highlight flaws. The market isn't going to do that. Time will prove the naysayers wrong. Take your own beliefs, for example. Only a few weeks ago you argued that Zelda is not a system seller. Now we have sales data from various countries and it clearly proves you wrong. And remember, the argument "people buy Zelda because there's nothing else" doesn't work, because that makes Switch and Zelda sales only more impressive; it effectively turns Zelda into a game that people pay $360/€390 for.