Because they have to support two systems at the same time but now, it can be like this:
2018: a remastered
2019: a new 2D top down Zelda like A Link Between World
2020: Hyrule Warriors 2
2021: another spin off like Tri Force Heroes
2022: another Zelda Picross
2023: a big mainline game
For the life of me i can't remembre what remastered Zelda game came out this year...
2019: agreed! It can be a more artistic game, btw.
2020: I can live with that
2021: Spin-off: Zelda inspired game (no, not the CDi games!)
2022: mainline game (it's 4 years after BOTW, i think it's enough time if they re-use the same engine)
2023: either a RPG or a remaster of an old handheld game (like the Pokémon Let's Go Switch game)
This is just an example. 2021: a spin off with multiplayer feature like Tri Force Heroes. Let Go isn't just a remaster, it's a full remake. 2022: mainline game only if they reuse the same engine, if they built a new engine then not sure it will take only 4 years.