I would be perfectly fine with starting a new game with better victory conditions. Fighting three wars off and on for most of the latter half of the game has indeed been taxing, not to mention my feeble attempts at diplomacy, and juggling a mid-tier blood economy off and on(at least the micro is better in Dom4). That said, if you want to do a big battle over there in the East, Dayyalu, it would probably be cool.
If not, I'll probably cast The Looming Hell and Astral Corruption in a couple turns, for no good reason other than I don't play blood and want to try them out.
We have some solutions. For example, everyone can build a SC and we got to duke it out in a province all at the same time (as we know, attack order is randomized). I would suggest to take one of mine or Abysia provinces, to avoid GoH effects. We declare the winner the last man/Demon/Elemental standing. Or we choose a man-sized contender. Fitting that the fate of Gods should be decided by mere mortals, after all.
Or we can simply battle in the East and then declare it closed. Probably you will win thanks to GoH in a direct confrontation, though. As you saw, even Flames of Niel do not cut down your troops fast enough.
So, I'd still like to declare at least a "technical winner". Is the SC proposal acceptable? We choose a province, we build a chassis, and in one turn we do the Ultimate Showdown.
And yes, Victory Conditions for the next match NEED to be more carefully checked. Thrones were introduced to avoid this, and I was not a great fan of the endless endgame. Plus Looming Hell and Astral corruption would render the game almost unplayable, and no fun. And I'm here to have fun, weird as it sounds.