That's why I didn't read the thread until after I had seen the episode!
My guess: Jack is brainwashed by the Chinese adn sent back as a "sleeper." My first thought would be that another agent would stop Jack from destroying everything and become the new "lead" for the series; but if Kiefer is signed on for three more, that ain't gonna happen. I still think that having Jack be "the mole" for at least part of the day would be an interesting twist. Who would be sharp enough to stop him?
George