My impression was there wouldn't be further rejoinings after this one. The ascians stated a few times that this was the final calamity to weaken Hydaelyn enough to allow Zodiark to escape his prison and take back control of the world. Given he had already rewritten the rules of the world before to save them from Meteion's influence, once Hydaelyn is gone then he'd just erase the shards and remake the world as the ascians wanted without having to go through the trouble of a rejoining.