Again, where did you hear that they'll be NPCs? I'm working off of the last panel from hell and nothing I heard there leadsme to believe they'll be anything more than what I described. Technically they'd still be NPCs since they're, in the broadest sense, still characters, just not ones that show up on screen. Your idea is certainly possible, but it's also possible that we'll be able to romance Kethric Thorm and redeem him. Is there anything physically preventing that? No. Is there any evidence beyond his existence that suggests it'll happen? Also no.
You do know what the term NPC stands for right? Whether something as undefined as the narrator or super defined as Kethric they are all NPCs...you can't play as the narrator or as Kethric. But my point remains...they are confirmed to be NPCs with interaction so it is entirely possible for them to be defined enough and present in places in the world where everyone could run into them.
