Sans has never been antagonistic to Kris once. A lot of people thought that Sans would be a boss in Chapter 5 due to the scene where he’s dancing with Toriel and supposedly having sex with her. However in retrospect it seems like he was trying to help Toriel away from the Knight and make sure she doesn’t get captured. He‘s also seen helping Kris by giving them the bread crumbs as a possible way to escaping being drowned by Noelle. Those are the reasons why I don’t think Sans will be fought in Deltarune’s future chapter’s.
