I think sales this year will greatly impact this decision. Call me crazy, but I honestly see 2022 as a possible increase in sales from 2021. 2020 was an odd year, that makes 2021 look like a decline, but I think sales are still moving in a positive direction. if 2023 proves to be close to 25m. I don't think there is any reason for Nintendo to Announce a new console.
Nintendo did make that mistake with the DS and it ended up really hurting sales, at the time they made the mistake because they thought the 3D gimmick would be a super hit. I am not sure if Nintendo is seeing something similar with a new console. I personally chose 2026 as the release of the new console (march 2026). The way I see it, or hope is that sales could go like this:
Total Sales: ~190M
I know this "prediction" can easily blow up in my face, but I see the Switch selling really well and Nintendo could just ride this wave a little longer to release something very special in a few years.