Though I don't think they would do it, a plot that involves bringing together the remnants of Zodiark's dark energies in order to re-create him or a similar god to inherit his will would be interesting to see. It would give the currently unaccounted for Ascians something to do. The felling of both major deities without a replacement for either is something that never sat well with me.
One thing is "killing magic" at the end of a single player game, as much of a letdown as that is. Another thing is "killing magic" in an ongoing fantasy world. Religion outside of Eorzea and more specifically Ishgard isn't nearly as developed as it could be, and it is further complicated by us knowing that there really aren't any true gods out there, except for the 12 which don't seem to care about much of anything.
Taking away both major gods while causing a lot of twists in order to prop up one and dedicating no more than an hour's worth of time in Endwalker to the other didn't help matters much. Now in 6.2 we'll have the Loporrits dancing atop the Crater of Martyrs to further belittle Zodiark's importance, angering fans of both him and the Ascians, while the MSQ continues to push Hydaelyn and Meteion onto us. Is it any wonder then why some people aren't finding this writing to their liking and are sceptical of what is coming next?
I think I will continue speaking my mind on things as they are teased/announced and hold them accountable by speaking out whenever what we see in game does not match what they say elsewhere. New characters didn't materialize in 6.1. This was not to the game's benefit. New characters are coming in 6.2. This is good and is aligned with what they said previously. It is our duty as the customers and consumers of this game to maintain and raise the bar of quality for this game. Expressing ourselves clearly and honestly is necessary for that to occur.