There seems to be multitudes of enemy encampments, and the actually sizable towns we've had a look at from the trailers implies there's plenty to be seen. In all honesty, I'm in the same boat as others who feel that a sprawling, natural environment might also serve the game well enough without a multitude of elements cluttering it. I want things to do, but with the rumored 100-ish shrines, enemy encampments, bite-sized environmental puzzles, and traveling characters and semi-randomized events, it sounds like there's plenty enough to do in this iteration of Hyrule already. While I certainly hope (and it already seems that this is the case) Nintendo has kept the world more dense than Twilight Princess and Wind Waker, I also wouldn't want every inch of the world to contain something to do.
I'd like to think some of Monolith Soft's influence and expertise came into play in that regard. With the FrontierNav, every hex of Mira (a world of arguably the same size as Breath of the Wild, if I'm not mistaken?) contained some sort of element that would tie into a story or side quest arc. While some of these were simple collection quests (which I truly hope Breath of the Wild doesn't use to pad its playtime), others built on long narratives that fleshed out the civilization as well as giving reason to go out exploring. If the Zelda team approached Breath of the Wild with the same mentality, I think Hyrule will give us plenty enough to do. Remember, there are also weather and climate effects that are going to factor into how you explore and overcome Hyrule.