Reposting a hot take.
There is no way that Avatar ends without some sort of Hyper-Nationalist army revolt against Zuko (Like Fire nation Yukio Mishima trying to shoot Zuko or something) or some massive genocide occurring in the mixed race / Mongrelfied section of the earth kingdom fated to become "The republic" led by Earth Kingdom nationalist feeling betrayed by their own government and I don't give a fuck what the comics say.
Imagine your just some fire nation grunt or even something slightly higher up like a colonel or general. After a literal 100 years war you have finally won and created your world spanning empire but literally a month later as your celebrating your victory the firelord basically dies offscreen and his totally pussywhipped and cucked son becomes firelord, Immediately gives away all of your victories and literally abandons a section of your population to probably be killed by the nation you have just beaten in fair combat in every measure.
Zuko is getting stabbed to death or poisoned by his palace guards and / or his body being thrown into a river by an angry mob
Now imagine your a earth kingdom citizen maybe some farmer displaced by the fire nation immigrants, Someone who was being worked to death in one of their prison factories, Someone whose whole village got burnt down. Now imagine learning after you supposedly "win" the war that you have now consigned a section of your country to continue being ruled by the fire nation settlers (It does not fucking matter what Aang and Zuko call it, that's all that 99% of earth kingdom citizens view it as) and the fire nation will not have to pay ANY dues for what they did, your King and the "hero" the avatar is totally compliant with this.
The earth kingdom is having Heavenly kingdom tier genocidal civil war