If the rumoured advances of DLSS 3.0 are true, it really will do wonders. Assuming the Switch 2 is still years away and Nvidia will use the next gen 7nm tech for the mobile GPUs, I can see the switch being able to run games at 540p or higher using DLSS without much issues if the ps5/xsx are aiming for 4k. Obviously at lower settings than both the Ps5/XsX. But we will have to wait and see since you can never know with Nintendo. I do have more confidence on Nvidia though with their hardware decisions...
I think Switch 2 may actually have 5nm available if we're talking 2023.
Apple is moving to 5nm this fall for their iPhones, in three years time for mobile chips 5nm will be a common and well worn in.
Maybe we see a version of the current Switch (and Lite) move to 7nm around fall 2021 in another refresh for example, 5nm for Switch 2, then the Switch 2 Lite could work at 2nm/3nm say 2 years later.