Like a lot of other folks have mentioned (such as javi741 who made a great post on the subject), I think 2020 was Switch's peak year. It's hard to compete with COVID-19, but also the government (least in the US) was giving out very generous stimulus checks which was likely being directed toward Nintendo Switch purchases. That wont be the same in 2021 and beyond (though we can never doubt the government's ability to give out free money).
I think what's going to really hurt Nintendo over the next year or two is the lack of Software. 2020 at least had Animal Crossing, but 2021 has really nothing. I don't think Metroid and Mario Golf are enough to push Nintendo through the holidays, and it may not be a very good year for them. 2022 should be better, but Nintendo really needs to get some titles out. Internally, they've been slacking since 2017, and you'd think their internal studios would have more ready by now.
I think the worst decision Nintendo made here was the stock buyback. Nintendo has way too much cash right now, and a buyback isn't going to move the needle much (the stock is down since this announcement). The reason investors are pulling back is because sales declined and there aren't really any big titles on the horizon. Splatoon 3 might struggle due to the online membership (Splatoon 2 came out when it was free), and BoTW2 is taking too long and hasn't generated the same excitement since its last announcement. So investors see the good times ending and their taking their gains and leaving. I think a smarter move would be (or will be), to make some acquisitions. Nintendo is having trouble getting things out, and adding a new studio would help fill in the games, or help with development like Monolith does. This would have also showed some growth potential. I think Nintendo does need to come out swinging in 2022 and with the upcoming Nintendo direct, to tell people that, yes, there is a bright future for the system.

Visit my site for more
Known as Smashchu in a former life







