Thoughout OB we have seen Team Odium on a winning streak. They have basically rushed Alethkar and taken over most of Roshar. This sure looks bad on paper. But compare for a minute not the land that is under control, but the armies of Odium and the coalition. Then we come to a different conclusion altogether. On the one hand we have lots of Parshendi. Sure there are a lot of them. But they all had minimal training. Numbers are not everything in warfare. Then we have the Fused. The name alone sounds terrifing. But their battlefield performance is abysmal. We see multiple times in OB, how one Radiant fights off multiple Fused. And storms even Moash kills one of them, even though he just had few months of basic training. He sure is talented, but still this says a lot about the quality of the Fused as fighters. This is because they are not used to their new physical bodies. Then we got Thunderclasts. They are a tough nut to crack, but Radiants with their healing abilities don’t seem to have great problems taking them down.
So… what do we have on the other side? We got roughly 70.000 Alethi warriors, who are known across Roshar for their experience in warfare. They are veterans hardened by years of battles on the Shattered Plains. They also got shards, lots of them. And they are pissed that the Parshendi have taken their homeland. So it stands now lots of armed peasant Parshendi against the fiercest war machine Roshar probably has ever known. Then we got the Knights Radiants, who are only increasing in numbers. Did I mention that not a single high-tier Radiant has been killed in OB? These guys just have the habit of surviving.
You could make an argument that the Fused are just such brilliant commanders that they will win anyways. I have serious doubts about that considering that the ablest Fused have not even manifested yet. This might not be a coincidence.
What I am going to argue here is that subduing almost all of Roshar under Parshendi rule has never been Odium`s end game. Instead it has been to invoke Hatred inside the humans and the Alethi in particular. This makes a lot of thematic sense. Humans are his original people from Braize after all. They are the original Voidbringers. He also chose Dalinar, a human, as his champion.
Let me project a probable future that would happen, if Odium gets his way. The Alethi want to take back their homeland, they are constantly worrying what is happening to their loved ones back at home (and their property…..). So hatred begins to boil toward the Parshendi. After their initial campaign in Tu Bayla they march in direction of their beloved home. At the first encounters with the Parshendi at the border to Jah Keved they gain victory. They are surprised how easy these wins have been. The Radiants have kept Fused and Thunderclasts off and they, though outnumbered, could punch through the enemy lines quite easily. Then they see what the parshendi, who were motivated by Odium have done to the Alethi in the borderlands. Slavery might have been the gentlest fortune a Alethi civilian could have gotten. Also lots of horror stories about the Parshendi are being shared. Most of them are untrue, but some of them are not.
Now a then crazy seeming plan brought forth back a year ago by Jasnah Kholin begins to get supporters; To exterminate all Parshendi that the plague of the Fused may be stopped once and for all. At least this is how they rationalize their genocidal plans. If Odium had gotten his way then Dalinar would have been his champion feeding these ideas. Kaladin and all Radiants in their right mind quit the Alethi expedition. Still after their initial decisive victories even this mostly Radiant-less force, which posses still a significant amount of shards goes on and mobs up all Parshendi resistance left in Alethkar. This is a war of extermination. Parshendi are systematically killed by the enraged Alethi. When the mass-genocide has been completed all of the Alethi armies have fallen into Odiums hand. They turn their attention now to the rest of Roshar. With the help of the Thunderclasts and newly formed human voidbinder, they can subdue all of Roshar.
The Radiants make a desperate last stand but, ultimately, they are on the losing side. All living Parshendi on Roshar are hunted and killed. They merely served for Odium the purpose of being the object of human hate. After they had outlived their use, he could throw them away. And maybe he hates Parshendi himself beeing the shard of Hatred and all.
So this has been my first post... It is really not a pleasent theory. But in my opinion it makes a lot of sense to see it this way, even if a lot or even all of the details are wrong. Ah, and english is not my native language, so I apologize, if this has been a bit hard to read.