I don't like the idea because it sounds very expensive and lacks some compatibility between models. The strongest I see a Switch Pro getting is Base Xbox One or Base PS4. PS5 and Next Xbox graphics are going to have to wait until the Switch's successor. Even then, I doubt Nintendo will make it that powerful. Nintendo has been graphically behind since the Wii, and behind on file storage since the N64.
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