Colossus

I think it's very possible that Yumi takes place so far in the future (plus timey wimey stuff) that Virtuosity is currently alive at the end of SA 5. I had another in my theory that the Night Brigade is working for Retribution and or Autonomy to try to find the dawnshards to let them break that shield around the Cosmere. I don't think Virtuosity is alive in TSM since that's getting closer to Yumi's time. ( I can see TSM being ~500 years after SA5, so only ~1000 years before Yumi). If Viruosity is gone I wonder how the shield is holding up. Also I suppose that a shard can be gone but it's Heralds still alive. Honor is "gone" but his splintered powers are still functioning.

So after doing some thinking I would switch around a few of the picks you made I would put Ishar with invention since he seemed like he was the most creative with the surges before coming to Roshar, and just in general the more resourceful (He was coming up with ways to invent new warriors out of the spren even though that was deranged) Kaladin with Mercy because he's a therapist Nale with reason because similar to what I said before he was trying to put logic over feelings when talking with Szeth and deciding the future of the Skybreakers. I want Battar to go with Autonomy. Firstly she's definitely up to something, trying to decure HER best interests over the other Heralds and also she's possibly a traitor. Theres a popular opinion that Autonomy is going to end up being a bigger threat than Retribution in the long term and Battar seems like she would agree to help Autonomy conquer the Cosmere. That leaves the Kalak free. We know that Virtuosity is gone at some point in the future so if they are not dead currently that means they die sometime between Stormlight 10 and Yumi, it's possible that the Herald that accompanies Virtuosity will also die at this point so we have to decide which Herald doesn't make it out of this alive. I think either Shallash or Kalak fits well with that.

Wow you really did the heavy lifting here! If I squint really hard I can see how Nale could be a herald for Mercy. He likely believes he is being Merciful to the original Rosharans by making his Skybreakers align with the Singers. Ishar being a Herald for Whimzy doesn't make sense but I really want to see him start popping out his dentures in front of the other Heralds LOL

I mean due to Retribution each shard could choose a herald to give a splinter to, in order to shield the Cosmere from Retribution until the various peoples of the Cosmere can advance far enough to prove a match for Retributions forces (Potentially Retribution is very successful in convincing other Cosmere groups to join him), then each Herald is the general for that Shards armies. This also provides motivation for more isolationist shards to still Connect to a Herald because if they don't... when Retribution is dealt with the other shards will have a Herald general and they wont.

So currently the new Oathpact made at the End of Wind and Truth is not really locking the Fused away on Braize but rather protecting the Rosharan spren from Retributions influence. This theory just says instead of protecting Roshar's spren, the heralds would use their connection to Odium and Honor (Retribution) to protect the entire Cosmere from Retributions influence.

The fact that Brandon has delivered canonical writing set decades or centuries after the end of WaT appears to place restrictions on what the resolution of the conflict with Retribution could amount to. Furthermore, the PoV character from TSM is an extremely intelligent worldhopper. I find it extremely hard to believe that something as universally impactful as shattering Retribution would not be brought up by Nomad (Or Hoid during their dialogue). On the other hand, Brandon has said that he views SA to be his "magnum opus" and I also find it extremely hard to believe that the ending of his Magnum Opus wouldn't be extremely impactful to the entire cosmere. So the future where TSM takes place has to be one where the SA is respectws with a dramatic, impactful ending, but the impact on the Cosmere at large doesn't really change the universe to be unrecognizable compared to the end of WaT (For example, shades still exist, dawnshards are still in 4 pieces etc.) One theory I have played around with is that Retribution is still alive, but is outside of the Cosmere which is being shielded by the Heralds. THEORY: So, there are 10(9?) shards left to oppose Retribution: Harmony, Cultivation, Endowment, Autonomy, Invention, Mercy, Valor, Whimsy, Reason, and (?)Virtuosity. (I know that by Yumi and the Nightmare Painter Virtuosity is splintered but, I'm not sure if this was stated to be before SA or not) We also know there are 10(ish) Heralds (This theory actually works regardless of if there are 10 or 9 shards opposing Retribution, since Battar is a wild card.) I argue that in order to prevent the chaos and destruction that would inevitably occur if there were an outright battle between the shards and Retribution, the shards bond themselves to the Heralds to push Retribution out of the Cosmere in order to give the people of the Cosmere time to make a plan to defeat retribution without destroying everything. I also think Retribution promised the night brigade he would fix what Odium did when he killed Ambition in exchange for bringing him the Dawnshards so he can break the Herald's shield. I haven't taken the time to think of which Herald would be the representative for each shard, other than the fact that valor is defined as "great courage in the face of danger, especially in battle.", and I think we all know that the Bearer Of Agonies to a T. In any case, do you all think this theory holds water? Let me know what you think!

I don't know if this is just oversimplifying things, but the command for Dalinar to "unite them" can only be achieved if: 1) Dalinar Unites them 2) "They" are United This seems needlessly simple but follow me here. Dalinar is, barring whatever "he is spoken for" mean, dead. So if Dalinar is supposed to succeed that means by the end of WaT whatever was supposed to be united is now united. The kingdoms, however, are clearly divided. Some follow Retribution and some follow the Knights. The parshendi are equally divided between the Fused and the Listeners. It doesn't seem like anything is united by the end of WaT, except one thing: Retribution. We have reason to believe that the commands to 'Unite them" aren't actually part of the visions and may not necessarily have been given by Honor. I think its possible some splinter of Adonalsium was telling Dalinar to unite Honor and Odium.