I kind of think that at most ONE of the crew is not one of the eight, and I don't think that's even that likely. Thatch could be a stranger, because of his story. However, the way this prophecy works, the eight are supposed to meet and travel together, and interact meaningfully BEFORE this turning point. That means there are very few people actually eligible for the roles.
The Peasant is the only confirmed role so far.
The Architect is the big reveal, so it could be almost anyone (I would exclude Thatch, Morgan, the dragon, the gnome (although...))
I like the Mystic being the dragon, that fits very nicely.
The Philosopher is most likely Aly, especially if she's not the Mystic.
The Vandal is likely Grynn. However, we could be surprised here - she might be the Soldier. So far, she didn't leave the path.
I think the Noble is Reina. If the elf is not the Architect, he could be the Noble. In a way, Thatch also works.
The Criminal is set up to be Morgan, but I wouldn't be surprised if it were Thatch.
The Soldier is, I guess... whoever's leftover.