I don't mind if there's not any NPC models in the overworld, heck in town I think it might be preferable for just everyone to be inside houses, makes finding people more easy. I just think that BaK had two problems with the overworld NPCs, first is that you can't see them, they just suddenly intercept you in an area you walk past, and if you need to find them again, you need to leave and enter the general area again. Kinda janky, and I never liked that they were "invisible" and just appeared out of nowhere. Second, you can't walk past an NPC area without them interrupting you, even if you don't want to talk to them. I think some sort of solution would be preferable to that, and the first thing that comes to mind is them just standing there as a model you can click and talk to if you want. Just put them in an obvious spot.
Of course, they can and should interrupt you at certain points as you walk past them if the plot demands it, just not all the time.
All of this assuming that you'll have overworld NPC's of course.