We wont be betrayed, we'll do the betraying. After all we also are Asciens and not just a "Warrior of Light", see how every one hint at how a betrayal from us would be awful. Why suggest things such as possible betrayal from someone who as been risking his/her life countless times to protect Eorzea and its people if it is not relevant at some point in the story. So yeah I bet on something like us being Asciens or something like that, this would also explain the vision we had of Zordiak coming just after the "Mother Crystal" left Eorzea and the "something else" that Ramuh felt when he was looking at us and saw we where a "servant of the Light".