I really hope we get a reactive world. D:OS2 was pretty static and rigid in what you could do but it worked with the story and didn't feel lifeless. Larian are perfectionists and their approach seems like it's really trying to be as true to form as a D&D game can get. I don't know how hard it would be to implement some passive reactions or get unique dialogues from doing things in proximity of certain npc's but I think that would be a neat feature. Like maybe you cast a light spell and characters with lowlight vision have to cover their eyes a bit from the brightness. Or maybe playing as a druid in wildshape caused certain npcs to get scared or even disgusted. I'm sure Early Access won't have too much but in the final release I don't think it would be THAT hard to get some dynamic flavor in the world this way.