Honestly I think it will depend on what NVidia has in store for them on when it will happen.
I think they will probably try to target for Switch 2 a 1080p 60fps portable mode (probably DLSS3.0 by then support too?? Maybe DLSS4.0 lol). If that means no release of new hardware till 2024 so be it as I do not think Nintendo is in a hurry to replace their hardware.
Will they do some sort of minor revisions that support DLSS2.0? perhaps but then they risk alienating games only being released with DLSS2.0 enabled
so they would segment the market if not games support the old hardware. In any case whatever revision they do will need to ensure that the launch Switch games are still supported until the true next gen successor comes out.