Switch Plus seems far more likely. The rumored Switch Pro sounds like a much better idea for a Switch 2. I really don't see Nintendo messing with something like 4K DLSS on a mid-gen refresh for the Switch. The only way that would happen is if Switch 2 comes out Holiday 2024 or later. After all, why release that big of an upgrade to your hardware if there's gonna be a successor by March 2024 or likely before?
Switch Plus could be the pro model. Better battery life, a slightly bigger screen, maybe 900p resolution, better CPU and GPU in the dock and tablet, more internal storage.
Lifetime Sales Predictions
Switch: 151 million (was 73, then 96, then 113 million, then 125 million, then 144 million)
PS5: 115 million (was 105 million) Xbox Series S/X: 57 million (was 60 million, then 67 million)
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima