So I have two theories I have been cooking up for the end of the first and second halves of the Stormlight Archive respectively. I'm pulling this from a post I made for Reddit, but figured I'd get more in-depth discussion posting here. I'll try appending the text from the reddit post below.
I believe Dalinar will reforge the shard of Honor during the contest of champions at Urithiru, whether out of desperation before losing, or for some other reason that I cannot predict. Such an ascendancy might void the duel, whether it be due to a vessel being unable to be their own champion, or because he is no longer able to be killed/kill his opponent. Moreover, this would likely make it possible for the resistance to Odium to survive until the second half of the Stormlight Archive, and for Odium to be kept in check enough not to have shown up in Mistborn Era 2. It would also explain the Cinder King's comment about Rosharians ascending to become gods.
My second theory is about Jasnah, and will depend heavily on the excellent Fractal organization scheme for shardic intent by wajeemba. I would highly recommend checking it out as it is a fascinating read with implications beyond this post. The key part of this is the true intent assigned to Odium in this scheme: "Righteous Anger/Fixing Wrongs", to which I will add "removed from its original context as contained in the other shards". This intent is due to the combination of the DESTROY/Passion intent with the CHANGE/create subintent. This explains why Odium can only express the destructive passions, and the more sinister nature of Odium (due to the CHANGE/create subintent) compared to the gleeful destruction seen in Ruin (double DESTROY/Passion in this organization scheme). It also explains why it so difficult to control. It is divine fury and hatred divorced from its context. Therefore, the consideration of what is right and wrong falls upon the vessel, and thus far we have only seen the results of that from a mad narcissist: Rayse.
Rayse was a good fit for the shard in all the wrong ways. A narcissist to the core, he desired nothing more than to be the one true god of the cosmere, and was all too willing to embrace the obsessive hatred that the shard encourages. His lack of any moral compass is reflected in the Unmade, specifically Ashertmarn (the Heart of the Revel) and Nergaoul (The Thrill). Both are expressions of his complete moral bankruptcy, encouraging blind submission to the worst instincts of humanity. The shard's intent also explains Rayse's ability to remove emotion from his executors like Moash, taking away the moral context of his retribution, just as Rayse has done with the shard. There is only one location in which he diverged from the shard: his hatred of questions, as seen in I-2 of RoW.
Sja-Anat mentions in I-2 of RoW that there is weakness "in the division between the Vessel and the Shard", and I believe Jasnah is the knife that will tear that seam apart and defeat Odium in book 10. For me, this argument hinges on a mix of metaknowledge and in-book knowledge, which I will cover now.
First, what we know from the text. Jasnah has been shown to contain a broiling rage at injustice throughout the books, demonstrated most prominently in her murder of the footmen in Way of Kings. It has also been borne out in her decision as Queen of Alethkar to free every slave in the kingdom, a move Dalinar was right to call insane to enact during a war, yet shows a commitment to her morality that is unmatched in any other character in the Stormlight Archive. The moment sells this most, however, are her actions to discredit Highprince Ruthar. She judge him unworthy and enacts an almost divine justice upon him, showing total hatred towards him all the while, a masterpiece fitting of a potential vessel of Odium. Her most key trait, however, is her ruthless investigations and love of questions, the trait Rayse was most incapable of accepting in the shard. This, I believe, is a seam Jasnah is perfectly suited to tear at, and I would not be surprised if she ascended to the shard by matching the shard's intent better than Taravangian in a manner similar to how Dalinar trapped Neragoul in Oathbringer. And bringing back a point from my section on Dalinar, Cinder King mentioned "people" ascending to godhood to Sigzil, not an individual, didn't he? Thus, I believe she will take up the shard, and finally give context to the divine rage of Odium, setting up a cosmere-wide cold war between a Roshar with three separate shards against Scadrial with a fused pair of shards embodied in Discord.
I will wrap this long post up with two pieces of meta knowledge which I believe confirm my theory. First, Jasnah is the last flashback character of the Stormlight Archive, suggesting an immense importance of her to the end of the series. Second, there is a Words of Brandon on the question of Jasnah fitting Odium, which I will quote:
RAFO indeed. See you all for the release of book 10 in 2050. I'll be waiting.
