That kinda has the ring of Amber, except we finally learn that Chaos isn't so 'BAD.' Still, there seems to be some schemes going on that Merlin as new Leader of Chaos has to learn about. Author died so we don't know where the series would have gone from there.
The Amber equivalent would be Harry becoming Lord of the Outsiders maybe to find out potentially there is another bad that has corrupted Chaos. This goes to the question of whether this is a story of Order vs Chaos, or is it a story of Order vs Chaos vs (HORRIBLE), or is it Order + Chaos vs Outsiders
Maybe the Outsiders were once Insiders that HORRIBLE has taken over to use against us in our multiverse. So, if Harry can take control of these "Outsiders" and use them to turn against HORRIBLE, then he can use Chaos to take out something worse.
It could make sense. Think of Cat Sith. Nemesis just apparently converted him from Fae to Outsider essentially in Cold Days. If Harry can free these recently turned 'Outsiders' and all of them generally, it would be a great accomplishment.