I'm love both TotK and BotW, but after a number of hours traversing the world starts to be a bit of a chore, specially when you have to return to someplace where you've already been so there's nothing new to find along the way. Vehicles alleviate this, but in the end I just teleport to the closest shrine. At moments like these I would like for the games to have some crazy movement mechanics so you can blaze through the world while keeping it engaging, like in Ori or Metroid Dread. But don't get me wrong, I still put both BotW and TotK at the top of the Zelda experience as they provide a sense of wonder I hadn't felt since ALttP or OoT.
I'd love for the next 2D Zelda to take the place of classic 3D Zelda (well, 2D Zeldas have already been 3D since the DS ones, you just need to be able to move the camera freely), with a tighter world and a more intimate story. I'd love for the whole world to be a huge puzzle you have to solve bit by bit, opening new shortcuts and paths as you progress like in the first half of Tunic or a Dark Souls level. They could be more like spin-off stories like LA or MM and use more experimental settings like dream worlds, aliens, ancient technology and such. And focus on a single, strong central mechanic like MM did with masks or ALBW with the paintings. Keep them laser focused, tight, weird and not too big.
And then just go crazy with scale on the 3D ones with the BotW template