They have escaped downfall by maintaining the order of this world, though the perverse way they choose to do it will result in their downfall by a yet higher power.

[ Does he mean Forneus? Perhaps. ]

We Archons are tasked with our duties by Celestia. However, Celestia itself is also beholden to a certain set of rules. Their fall will require a longer time than that of the Archons, just as how the downfall of Archons require a longer time than that of human kings.