I just don't want it to be the same map, even if it has new things in it. I spent close to 200 hours scouring that map. I know it like the back of my hand. How can there be a wonder of discovery if I already know the lay of the land?
I've been thinking about this all afternoon, and I keep going back to how great it is that BotW has memorable world design. In 99% of open-world games, I'm almost entirely reliant on the mini-map to know where I am and where I'm going, and consequently I never really feel like I'm part of those worlds. Like you, I know BotW Hyrule like the back of my hand, and it was the first game of that scale where I could turn off the map and know exactly where I was and where I was going. That familiarity and sense of place was huge for me, and really made me believe I was a part of this huge open-world for the first time.
I think having that familiarity and that sense of "this is a believable world that I know all about and lived in" right off the bat is a really compelling place to start in a direct sequel.
So how could they provide a similar sense of exploration and discovery in a game where you already know the layout of the land? I think in a more content/puzzle-driven game, that's something they could pull off by using your built-in knowledge of the game's world as a tool/resource at your disposal (i.e. you have the full map unlocked so you know where all of the locations are, but the sequel would emphasize you having to figure out on your own where you need to go and what to do). For example, the puzzles offered by the Shrine Quests in BotW were largely brilliant and one of the things I enjoyed most about the game; I'd love it if the sequel was built around more of those sorts of objectives.
In essence, they could make up for the game world itself no longer being a mystery by threading all sorts of new mysteries throughout the world. Where knowing the ins and outs of the map would be a good thing, rather than a bad thing. (And if the trailer was indeed teasing new areas underground and/or in the sky, that could supplement the existing map layout in other meaningful ways).
