All right, we'll do it that way.

---SPOILERS FOR AFTERMATH---

Over the course of the book, there are passing references to a recently deceased fleet admiral that Rae Sloane had previously served under and has now sort of taken over for. In one of the final chapters, she reveals to a Moff character she'd been butting heads with the whole time that she lied and the old admiral is still alive. The epilogue is her reporting to this fleet admiral on the bridge of his Super Star Destroyer. He's never named or described physically, but when we see him he's humming along with a symphony and won't let Sloane speak until it finishes. Sloane questions him about the events that have just happened and he implies that he orchestrated the entire thing, down to leaking info to Ackbar. He tells her this whole thing was a test to see who among the Imperial top brass was worthy/useful, and that she alone passed. The art appreciation, the elaborate gambits, the quasi-legendary status of this guy among the other characters, the hints about the Unknown Regions, even the way his dialogue is worded has all got me thinking this has to be Thrawn. I seriously doubted it at first, but if that's not where they're going with this why lay it on so thick? I think it would be a huge mistake to create a new character as a Thrawn analogue because he'd be destined to only ever be unfavorably compared to Thrawn. The more I think about it, the more sense it makes. So yeah. We might have our first survivor of the canon purge.

---END OF SPOILERS---