I forgot about NSMB Deluxe coming out earlier this year. The thing is The Switch Lite will be available for all of 2020, while in 2019 it is only available for 3.5 months. Sales should be up year-on-year through summer 2020. Animal Crossing is bigger than any release in 2019, other than Pokemon Sword / Shield. I expect a lot more Japanese games coming to the Switch as it is the only platform that is still selling well there.
I dont really see Japanese support changing in any major way. Up to this point it has mostly been smaller niche titles, late ports, remasters and the occasional medium sized exclusive.
The next mainline titles in the big franchises like Monster Hunter, Final Fantasy, Dragon Quest, Resident Evil, Kingdom Hearts, etc are years away from releasing so that's not really a factor for Switch next year.
In terms of system selling 3rd party titles, it would either be some surprise hit new IP or a collaboration on a Nintendo IP.
And I agree that Lite+Animal Crossing will keep it up YoY in Q1 & Q2 but depending on what releases in Q3 I could see it being down (still up YTD though). Mario Maker, Fire Emblem, 2D Zelda, improved model & Lite model is tough to compete with. Then Q4 I expect to be down unless they have some really aggressive holiday deals.
When the herd loses its way, the shepard must kill the bull that leads them astray.