After taking some time to read WoB, He intends for one book to focus on one KR order and one POV character but the POV character does not necessarily have to be a KR. Also, Brandon even included Adolin & Navani as one of the major characters with POV initially. Possibly due to too many potential POV characters, 10 KR, a couple of Heralds, a parshendi etc. He could be planning to condense Adolin's & Navani's background stories with Renarin's & Dalinar's.
Another important realization as I read through WoB was that Brandon stated ALL the KR are humans and the parshendi are not humans. While I dont think parshendi could be reverted to humans, we will need to RAFO more about parshendi history. For now, these two facts rules out Eshonai as one KR, she is just a POV worthy character incorporated into one of the books that focus on one of the KR, likely with a relation to her story.
And somewhere in WoB, Brandon also stated he wanted to include another Herald's POV, someone he hasnt decided on yet. Considering he once viewed Navani and Adolin as important POV characters and he claims that we have met everyone, I am now speculating that Navani is of Willshaper and Adolin is of Dustbringer! Navani and her fabrial technology advancement might be plausible with the oddity & enteprising descriptions of the Willshapers order but I wont discuss about her in this thread that much.
As for Adolin and speculations about turning evil, i disagree. It was rage (Dustbringer fiery justice i imagine) and perhaps instinct that lead him to strike Sadeas to prompty remove a dire threat to the ones he love. (Sadeas had Dalinar, himself & even Shallan almost killed, on multiple occassions) Adolin did not "lose his control". His reaction on "killing a high prince" and his attempts to cover up his involvement were more of a worry about the political ramifications for him or more so for his father.
I believe he will admit his actions to Dalinar (or keep him in the dark to protect him), Shallan and Kaladin (who would likely both understand what he did.) So I think his actions would only endanger his relationship with Dalinar at most or his political standing (I doubt he cares much for but Amaram/Sadeas got away with much more). He might need to watch his back against Skybreakers or Sadeas's wife I think.
@maxal
It could the case that Adolin's journey to becoming a KR is worth the suspense but I wont be surprised if all the KRs are revealed in the nxt few books, considering about half are already revealed by book 2.