Also im not sure where you are getting all this lore about Volazj. For all we know his mutterings could be the ravings of a fanatic and im not sure i entirely buy your entity theory. If they were an essence then why would they take corporeal forms leading to vulnerabilities like being imprisoned by the titans or getting beat up by us. Elune is the moon goddess so im pretty sure if the moon were to be destroyed she would go along with it. Their continued existence after death may just be because there are other Old Gods left alive keeping their spirits from completely leaving.