Isn't a god only as strong as it's sphere is important?
In Mundus: yes. Overall: no.
Auriel | Akatosh | et cetera was the most powerful et'ada. He beats up all the moments that haven't yet been caused to happen, putting him at orders of magnitude of higher power than any other spirit. Even the other gods within their realms seem to be somewhat under his influence.
Currently, Auriel is pretty powerful, but he's no longer the absolutely most powerful. A few individuals have won fights against him: the Tribunal, the Marukhati, and the Numidium. He's losing power, and someone else will have to take his place. Now, we haven't really seen much of Peyrite's raw might, but given his description of 'ordering the lowest orders of oblivion' it's possible he just might be the spirit to take the job. Remember, Oblivion is the chaotic realm - ordering it is a lot harder than ordering the anuic side of creation. Plus, its possible that the lowest order of Oblivion (an abyss) could actually be the most powerful / supreme area. God stands on the highest cloud of heaven | Satan reclines in the deepest pit of hell.
Once this Kalpa is done, the spirits who fought in this arena will be wiped. They'll spend centuries recovering from their deaths. In the meantime, a new group of spirits will take their roles. Basically, I think there's going to be some cross mantling going on. When y=x and y=-x intersect, you can't really tell if that's what's happening, or if y=|x| and y=-|x| are intersecting, or if |y|=x and -|y|=x are intersecting. That's how the myths we know have missed out on this. Shor son of Shor was wrong, in a way, when it said, "Shor as always forgets the above, and condemns himself and any other who would believe him into this cycle" but in a really understandable way. Last time around, there probably was a different et'ada responsible for tricking the world into creation, but mortals don't really care.