Just my personal gut feel, but switch by a couple of years. It doesn't feel like this generation (series X and ps5) has even really hit its stride. Significant fidelity upgrades are expensive, as such I don't see the series X 360 or ps6 launching any time before 2028. I think this generation will last longer than many are predicting.
On the flip side, I fully expect the Switch 2 to be fully BC (including digital), along with being well priced. I think the S2 will quickly cannibalize the switch, especially since the graphical upgrade is going to be massive comparatively.