I've been popping up here and there like the mole in Whack-a-Mole, spouting off that Number Six's Last Bastion arc be opened up to Goldsiders who reach Incarnate levels. Others have suggested that needs an in between addition explaining how those Goldsiders got to be Incarnates, and that's doable too with a short arc/mission set. The point being that Last Bastion proves that there are survivors free of the Tellurian Plague, ordinary citizens and members of the IDF, Powers Division and Resistance, still fighting on against Hamidon in an attempt to reclaim their world.
Imagine the Magisterium remodelled to include the devastation from the iTrial, and once you hit level 50 that's the only version you can access without going through ouro? Though I imagine the Underground would be mostly intact since those were originally nuclear bunkers anyway. First Ward would be a good template for this.