The end of the series

As we come closer to the end of the light novels, I feel like the end is upon us. However one thing remains mysterious, how will the novels end?

I feel like with the relatively abrupt ending of the series the ending seems somewhat obvious to us. As Ainz prepares to level the Slane Theocracy in the last novels, it feels somewhat anti climactic that in the end absolutely no one can stand up to Ainz and Nazarick in the slightest. PDL realistically poses no threat to Ainz and Nazarick, of all the powerful entities we know in the New World none could mount a surmountable defense or attack on the denizens of Nazarick. If we count the 8th floor Hierarchy and Rubedo those standings are even worse. However I don't think Maruyama will end it so simply.

What do you think will be the final plot twist of the series?

We know no players will arrive from the guild and I hardly think we will get some sort of betrayal from inside of Nazarick even though Nigredo hints at these things regarding Rubedo. Could we expect something outside of what we know?

The Catastrophe and Deep Darkness Dragon lords could be more powerful than PDL and we still don't know the power of the Dragon Emperor. He brought them into this world, could he erase them? Rigrit told PDL that he could have been the most powerful being so he obviously isn't. Could we see an appearance from the Minotaur Sage or Rufus? We don't know exactly who came into the New World in the intervals outside the 8GKs and 6GGs. I personally don't believe that the Theocracy will pose that much of a threat to Ainz so something must come up. What do you guys think?