Therefore, on the WiiU, the Gamecube ports would be the best solution. Wind Waker HD was well received (btw should also come out on Switch).
Switch 2 will definitely have a harder time. Nintendo will still be able to successfully release remasters and remakes, but they will no longer be such a driving force for console sales. Which does not change the fact that such BotW 4K would sell great anyway.
The benefits of Wii U ports right now should flow on to the next Switch. They're not only giving these games/franchises that were buried on a dead console more exposure (increasing awareness for future games), it allows them to easily pace out any big games in the works, giving the Switch a longer potential life and more time to plan/prepare for it's successor.
Whenever Switch 2 does come around, they should have a more than comfortable system for how they can schedule big releases to meet demand, along with how many ports/remakes they'll want in-between (obviously less than they're currently getting away with).
Right now, too many people are somehow interpreting Nintendo's silence to mean lack of production from their studios. I'm confident once E3 2021 comes around, assuming the world is back to normal and they do a big E3 Direct, those concerns can finally be put to bed.