the exarch had the perfect send off with telling us to take his soul crystal with us on our adventures while he's "guarding" the tower and, if they wanted to "revive" him in the body of graha, it should've had side effects or maybe be part of some hail mary to an unsolvable problem
then again, the plot point of yshtola depleting her life aether to "see" has been ignored the second after it was introduced, so I doubt it'll ever be a thing again (and would honestly feel pretty shoe horned in at this point imo)
I hope they send off yshtola to the first to be with runar and for graha to take a more withdrawn role (tho my bet is that he'll continue to play a part past endwalker)
maybe thancred could open up an orphanage or something