First off, at the end of Oathbringer does Szeth bond a spren? I don't think he does.
Second, i think that a Shin with bond the Nightwatcher. It is mentioned in the book that the Shin kinda worship or worshiped Cultivation, and since the Nightwatcher is a "peice" of Cultivation. It would also serve as a way to bring the Shin more into the story.