I believe he will be playable in Snezhnaya because:
Bro is the 1st of the Fatui Harbingers. Now that his story as a Khaenri'ahn has been concluded in 5.x, and with the Fatui basically being absolutely cooked - >! the 2nd is completely dead, unfortunately!<; the 3rd has left the organization; the 4th seems to be ready to sabotage the Project Stuzha - Capitano, with all the Mistilteinn hopium and the Mare Jivari foreshadowing, will retrieve the remaining Gnosis from the Ley Lines and lead the Fatui to their ultimate victory in the upcoming war against the Heavenly Principles.
As for the source of his power? Bro's gonna use the Seven-Shifting Serpent technique, just like Skirk, but this time, with Khaenri'ah no longer being that far away, they'll implement some mechanics related to the next region into his kit.
With all the other candidates eliminated, Capitano will become Snezhnaya 2nd half' main push character, by awakening in the middle of 7.x and becoming playable in 7.7, when the Fatui' war against the Shades will finally be close to its end.
