Stuff like Xenoblade DE and Paper Mario were probably mostly finished before lockdowns started so it was easier to still polish them up in time for release, but for something like Breath of the Wild 2 which probably still has major parts of the game that need to be completed, losing several months is huge.
We can be almost certain Paper Mario: Origami King was pretty much done earlier, since it could be pre-loaded two months in advance right after they announced it.
On the bright side, 2021 might be STACKED.
Not to be pessimistic, but I think delays will stretch well into 2021. I wonder if Nintendo will try to plug some holes in their line up, by releasing Brain Training Switch in the West, or perhaps translating the Famicom Tantei Club detective games.
If they want to keep up monthly releases, something like this could be feasible I think:
September: Pokémon Crown Tundra expansion & Cadence of Hyrule expansion 2.
October: Pikmin 3 DX, Animal Crossing update & Cadence of Hyrule expansion 3.
November: Detective Pikachu
December: No More Heroes III
January: Brain Training Switch
February: Bravely Default 2 (I'm thinking this gets delayed out of 2020).
March: ...Famicom Tantei Club??? (unlikely to ever get translated, but seems like something they could spin up now.)
Sprinkle in a Smash Bros. character or two, push some third-party games harder (Final Fantasy Crystal Chronicles, Sakuna Of Rice & Ruin, Jump Force, Doom Eternal), add N64 games to Switch Online... I think they could coast like this for a while if needed.
Could of course be expanded if things like New Pokémon Snap, and the Pokémon MOBA are progressing well, plus there's always the potential for things waiting in the wings. But as a worst-case scenario where they can't develop anything else, I still think they could get a lot of mileage out of the currently announced stuff.
Would be great if Bayonetta 3 and BOTW 2 could launch in October and maybe November/December 2021, though. Metroid Prime 4 I don't see happening anytime before 2022, especially if COVID continues to ravage the U.S. Though this is all uneducated speculation of course.