Elesia?
I was hoping for Elesia earlier, but they announced Powerd Ciel... Two new Ciels in one version of the game would be epic, though, lol.
As for the boss character that has turned into a normal character mentioned above; are you sure they're not talking about Powderd Ciel? She fits the description better than Archtype or Osiris or G-Akiha (Unless they mean GVS-Akiha
).
Since Elesia is out of the picture, I'm hoping for the real Shiki Tohno. That way some new player can say they play Shiki, and I can ask "Which one?" then they reply, "The male one," and I ask "Which one?" and they reply, "Shiki Tohno," and I ask "Which one?"