Regardless of the reasons, no Nintendo system that has, after experiencing several consecutive quarters of growth followed by several consecutive quarters of YoY losses, ever experienced another period of growth. Once the growth gave way to losses, the system was post-peak (this isn't always the case for PlayStation & Xbox, for reasons too complex for me to want to get into at the moment).
The Switch's sales growth was already clearly slowing down, and it's already down two consecutive months so far. If it continues to have YoY drops well into the year, that will effectively signal the Switch's transition to post-peak in the U.S.
And I don't expect Animal Crossing to do wonders for Switch sales, either. It may provide a decent boost for March, but that's it. If you look at New Leaf's performance in the U.S., it sold only 1.36M copies in its first 12 weeks, and its effects on 3DS hardware sales helped it for maybe two months at best and even then only relatively modestly, with Pokemon X & Y being a far better system-seller:
I have to admit I probably got a bit blindsided by Japan as Animal Crossing will have a huge impact there.
But did not quite realize that this is US only.
Still think that Animal Crossing and its special Hardware version can make this quarter a YoY growth. After all the drop in January and February has not been that big. Afterwards the Switch has its usually weak Q1 but Animal Crossing should help there. I expect New Horizons to have better performance than New Leaf.
And after that I expect it to drop.