Power-wise I'm thinking PS4 Pro level power. 1080p screen. 4k capable when docked. Hopefully a small enough gap from the other next gen systems to get more support from 3rd party graphically downgraded but still good AAA games than Switch.
^ that cannot be done with todays technology....
I think maybe you can get a Switch 2, thats around where the Base PS4 is (when docked).
That could probably be possible in 2021.
That would mean Switch 1 -> Switch 2, is a jump of x3-4 times in terms of power.
Well thought out. I would add bluetooth functionality for head phones and accessories. Larger storage capacity right out of the box. Fixing the Joy con drift issues would go a long way ( after two years of use my right Joy Con is starting to drift.) A 1080p screen with HDR. PS4 like horse power will be a significant leap in Nintendo first party games so that would suffice.