So, Aonuma has confirmed that we will be revisiting the same Hyrule in BotW2 as we saw in BotW.
A 3D game has never reused an overworld in Zelda. And it has only happened once before in the 2D games with ALttP and ALBW.
I've put 500 hours (I know, I know) into BotW and I'm sure others have...