You know what would be interesting? In the advent of the 3 other gemstones, at level 100, we'd get an action that unlocked a special board (out of combat) circular interface where you could change the placement of each gemstone and Demi. Unprecedent feature, and highly unlikely, but it would add some nice interactions in that you have specific setups for different fights.

More realistically, if there's one old thing that I really wish reworked is the aetherflow system of SMN, because it just feels like some awkward remnant of the old SMN that works... but feels out of place (Festering... what exactly, since there's no dots anymore?).

I think I'd go along with any idea, as long as it could be more cohese with the rest of the kit.