Between the seeds they've sown about using the First's excess light to fix the Thirteenth (which they made a point of mentioning again in 7.5), and the fact that every single reflection we've seen (now including the Fourth) is elementally out-of-whack, I'm pretty convinced that, at some point, we're going to end up creating some kind of giant, IRL version of the elemental chart Urianger showed us in Shadowbringers.

Though whether that would actually help with our "oh god everything's rejoining by itself" problem, I have no idea.