BotW was amazing with a giant world to explore all over, but sometimes it was light on things to do/find/see. It is always fun but if there was one thing that was lacking it was variety and amount of content to fill the enormous world.
Sometimes in BotW you're exploring a whole remote area and there is nothing out there except for the occasional animal and maybe a korok seed somewhere. I want to see that type of thing in TotK suddenly have, for example, you come across a decent sized cave to explore with enemies and items to find, then you leave the cave and after exploring you turn a corner and you get ambushed by a few enemies who set up a trap for any passerby, then you escape them and you find a pack of animals to hunt across the terrain but after couple minutes you get distracted by some spirit that pops up out of nowhere and gives you a challenge to do to get some cool weapon, then you finish that and you see something a bit in the distance and it's an NPC who needs your help. Granted obviously BotW has plenty of things types of things spread around, but I want to see TotK have enough content so that this sort of thing gives you some interesting things to do even while you're exploring remote areas that don't seem to have anything in them.
ToTK development likely started in early 2018. That's five years of development on the sequel in which they already had a ton of the assets they could use from the first game, most of the controls and physics and animations and game mechanics that can just be re-used, and they are using the same overworld just with lots of changes to it, in addition to being able to skip the initial planning phase where they figure out what kind of Zelda game it will be because it's a direct sequel to BotW so that's already figure out.
That's an absolutely enormous amount of development time they can skip for TotK compared to BotW. Given that, I would have to guess a lot of the 5 years of development on this game has gone into filling up the world in a way that BotW didn't have. It'll be interesting to see what kind of content TotK will have, but I bet it'll feel filled to the brim with the variety and amount of things to do and see compared to BotW. If not...well I'd question why the game didn't come out in like 2020 haha.
I'm hoping to see more enemies and a much greater variety of enemies, more hidden things to find, maybe something like animals moving in packs or herds, more hidden places to explore, more encounters with NPCs out in the world who give you things to go do, full-on dungeons in addition to shrines, more mini-boss battles to find in the world and big major boss battles, new game mechanics, hopefully a more streamlined cooking experience, etc.