Most bizarre revelation of Kai is not the daft time travel shit but that people who speak an unknown language can appear from the Beyond, and for whatever reason it happens every 1200 years and it's always a child.

If this isn't some esoteric stunt pulled by Aidios for example then I'd like to know who's behind that stupid shit. If time in Zemuria doesn't run faster, almost 24.000 years have passed beyond the barrier. Surely they grew tired of their rituals at some point.

I also expect that McBurn will be in the last game because he was frequently mentioned and even depicted. Ouroboros probably plans to take the Chest for their own ends (the snake biting its own tail), just like the Grandmaster also needed the Aureole. (Note: Spacetime.) The new Aion is meant to allow McBurn an assult on the Sept-Terrion (the evil mecha is clearly demonic in nature). It's also possible that the large shield in Ouroboros' emblem is a reference to space (which is often depicted as a plane).

Furthermore, given that the Church has access to knowledge which should only be found in the Grand Archive, it is quite possible they are successors to some cult which originally started the loops. They could have been punks who begun to worship the Sept-Terrions as salvation after people started nuking each other. They made sure that after the first Reset there was going to be a group that would collect the artifacts (hide the truth) and tell people to venerate the Goddess. This is like the silly Wall Church in Attack on Titan.

That's why Ouroboros and the Church are enemies; the Grandmaster is a heretic who left the cult and intends to break its stranglehold. It should be noted that Ouroboros is prone to rituals and esoteric symbolism.