My impression of Cole was that he'd changed substantially once he realized he wasn't really Cole. Before the Litany of Andralla situation, all he remembered was Cole, the mage boy that died. At the end, he realized he wasn't really the boy, which is what he tells Lambert. I think the Cole we would get, if he makes it into the game, would be more like an adult, because otherwise everything about taking him along would be weird. I think most likely his character arc will revolve around him swinging towards either the "good" path (helping people) or the "bad" path (killing people indiscriminately) now that he reached a higher level of general self-awareness.
Of course, that's just one theory. I'd love to see him in the game regardless which path they take with his personality, because I'd love to learn more about spirits without having just vague comments filtered through a possessed person. Especially with the veil tear being the major issue this game, I think his perspective could be really interesting.