I change quite a bit my post, so if you can reply to my changed post. Also, thats huge drop from 18m to 11m, I dont see thats kind of drop is possible in 4. year on market for Switch. Only around 10m more than 3DS sound to little for Switch.

Your 2019 and 2020 FY are very optimistic for my tastes. There's where our main differences come between us. 

And yes, I expect a huge drop in shipments in FY 2020. By 2020-2021 I expect Switch saturation mixed by next gen hype absorbing all the attention by the people who buys switch only as a home console. Remember that sales and shipments doesn't work the same so that's why expect some differences between sales and shipments with more sales than shipments in some years. 

Maybe in 2020 I was too low, maybe 12M instead of 11M and 9M instead of 10M in 2021 would be better. 

They overshipped this last year right? compaired to sales.
So.... Im guessing it ll be around 18m? or so for 2019.

I voted 25m, because I know they can beat that this year.  Don't know what they will forecast though.  They might be more conservative and only forecast 22m or some smaller number like that.  Regardless of what they forecast, they are going to beat it.  This coming fiscal year, Switch sales will only be limited by whatever Nintendo can produce.

It's going to go from a 40% drop in FY20 to a 10% drop in FY21? That's an odd sales curve.

What makes you think it was overshipped?

Like miyamotoo pointed out later, it was a weird sale drop curve indeed. The fact that I was doing that numbers by phone while watching a movie did not helped. I said later that 12M in 2020FY and 9M 2021FY is a better prediction. 

I gave you very clear points why 2019. can be around 20m, also that fall from 2019. to 2020. is really huge in any case. But yes, you definitely have pessimistic view for my taste. :)

Next gen will have atentione on lauch, but Switch will still have own market despite next gen consoles, biggest strenght of Switch will be peserved in any case, and thats hybrid concept (handheld play) and Nintendo Switch exclusive that are very popular, not to mentione that buy time PS5/XB2 arives with its price points of $400+, Switch will have around $200 price point with already built very strong lineup of games. Shipments and sales are same at end, if you look Nintendo numbers for every platform, they are all shipped, that goes for Switch, 3DS, Wii U, Wii, DS..

https://www.nintendo.co.jp/ir/en/finance/hard_soft/index.html

Even 12m going from 18m in one year is huge drop for 4. FY on market, that kind of drop (33%) not even Wii had in same period, that kind of drops are usualy at end of console lifes. 3DS had that kind of drop in its 4. FY on market because 3DS had very early in life huge price cuts and revisons, and later those things couldn't effect too much on sales, thats not case with Switch, Switch is entering its 3. year on market without price cut and revision, even without bundle with one game for launch price point.

What I'm pretty sure is that switch is going to sell way less in 2020. So if you find going from 18M shipped to 12M shipped too much then maybe this year is going to be 17M instead of 18M.

If switch sold 16'5m last year I expect switch around 17-17'5m in 2019 because despite expecting more sales in Japan, I expect less sales in Europe and flat sales in USA.

And for 2020 I really expect switch selling around 12-13M so shipments has to be somewhat similar but if in 2019 shipments go too high, in 2020 they need to be a million or more lower than sales. That's my reasoning. 

23M , Nintendo has many more titles for 2019 than they had for 2018, FY2018 will close with 18M so 5 more milions isn't that unrealistic to achieve, especially if a new version of the Switch is planned like many newspapers reported