BOTW was an experience! The ONLY thing that would make it better for me would have been virtual reality.. I think it would have been the end of me.. Anyhoo, I actually think they should build on BOTW. Take that whole environment and make that a playable portion on the next game. Basically you open up the lands beyond the boundaries of the game. The lands to the north past the canyon, on the other side of the desert, over the mountains to the west, across the sea to the east and south. Could you imagine 4 more games, each game representing the 4 other directions and creating a globe of interacting worlds that lead to each other. What if they could take the already existing BOTW world and have it play a part in the next game. Update it, add hidden dungeons in previously inaccessible areas for new weapons, new abilities. You could play in the new world, but still interact with the original BOTW world. By the end of it all, you would have a game so EPIC, if you had never played any of it, you would be hard pressed to even complete all 5 worlds.
That's what I would do.