Maybe he’s cooking something up to “reforge” the Titans themselves as they did to his kind? Turn them into a new pantheon of elementals? Who knows? Blizzard rarely does thematically predictable plot beats, which makes them (obviously) difficult to predict. Which is more the point than telling a cohesive story.
I like what we already saw of him, but I assume I’m going to be disappointed when he reenters the story.