And here's a big idea I've had floating around in my head for a while:
Despite some evidence of dissent Varea's Amagal seems stable and on an improving trend. Begus seems to have an ongoing storyline with corruption in the church, but it has a sympathetic ruler and its problems seem fixable. That leaves Dorgania.
King Lancafew says slavery in Dorgania is a necessary evil for the country to survive. In a way, he's right. Only with the cheap labor is the mostly-desert country able to farm enough food to support itself. Even if the rebels win, they will be faced with the same choice. But as a vassal state of Central, it would have the excess food produced by more fertile lands while in return giving access to mineral reserves and stuff like that. Arguably, that is the best option long-term for the Dorganian people.
One possible way to work towards annexing Dorgania would be from Palasha. She could, through an alternate ending to her storyline, be turned against her family after seeing what a comparative paradise Central is and realizing the stuff in the paragraph above, that the slavery and suffering she's been trained all her life to ignore is truly not necessary. Having an informant literally inside the royal family, could go great lengths towards ending the war with as little bloodshed as possible. Maybe towards the end she sneaks out at night and opens Kagabangui's gates, allowing a strike force (vanguard battle?) to storm the palace and force the royal family's surrender, and likely saving lives on both sides by preventing a prolonged and costly siege.
Maybe there could be some interesting stuff with some of the rebels (the ones that attacked Minsk?) being more in it for the power and wanting to just replace the monarchs themselves, or just wanted anarchy, which could create some complications after the war proper has ended. And does Mike know Ryen is the king of Central? If not that could be a pretty fun reveal.
Ok the ideas are out I'll stop infodumping now have a nice day