Nintendo's problems in part are due to software development starting too late I think in a lot of cases.
If I was running Nintendo I would have insisted (not asked, insisted) that the Mario Kart, Animal Crossing, and Smash Bros. teams must be working on hard development (not just planning, but actual level/world building, etc.) successor franchise installments of those IP for the next generation no later than January 2022 already, so the next installments of those games should already be well over a year into development already. I don't know what the Mario 3D/2D teams are doing but they should also be not only well into development of their next game but well past 50-60% complete.
You shouldn't even really need finished hardware for that as you can approximate what the next system's hardware would be like and use an older Nvidia graphics card to at least begin development on.
Everybody got a break most likely over the COVID break, and the last installments in these IP are now years in the past, it's time to get down to the nitty gritty of making the next franchise installments.
Gotta have content and the next transition will be harder for Nintendo because they're not going to have a Wii U library that was largely unplayed by a lot of people to pick apart and repurpose for easy hit titles in year 1 (ie: there's not gonna be a BOTW or completed Mario Kart 8 just laying around this time).
This October it will be 6 years since Mario Odyssey, ordinarily we would already have gotten the next 3D Mario, which makes me strongly suspect they're holding onto it as a first year game for the successor.
Mario Kart 9 should also be very far along by now if Nintendo have any common sense.
I am skeptical if Nintendo will want to entirely let go of their 120 million plus Switch userbase right away though, specially considering the 3DS saw support for a 2 years after the release of the Switch.
They are either sitting on a new 3D Mario for this fall because of the movie or holding it for the launch of Switch 2.
Mario Kart I think is the most important Nintendo IP, even eclipsing the Mario platformers at this point, MK9 (or 10 if you count Tour as 9) has to be deep into development right now unless Nintendo has lost their marbles. I would want that as early in the Switch 2's product cycle, even day 1 if possible (since you're not going to have a new Zelda).
Even Animal Crossing and Smash Next, like I would want those to be in actual development by now, not just sitting around a table and discussing ideas. That should have already been what those teams were doing over the COVID pause.