I wouldn't rule out DLC but knowing Nintendo, I wouldn't count on that happening right away. I'm quite sure they'll focus on making sure the game feels quite full to begin with.
I'd love to see a range of dungeons that can be completed in any order, though. Either slightly, like Ocarina of Time did with the Spirit and Shadow Temples, or more expansively, like A Link Between Worlds did. It would really allow the player to explore the world however they wanted.
I'm certainly hoping for a range of different terrains, too, which could potentially set it apart from a lot of open-world games that get kind of samey. Volcanic areas, mountains, snow, dense forests, lakes, meadows, cities and villages, canyons, caverns, swamps...
Otherwise, I'm not thinking too hard about what I'd like to see. So long as the world is interesting to explore one way or another, I'll be happy.
