My personal bet is Secretary of Defense Heller.
And no, that isn't based on any information I've heard except the fact that he is supposed to be back sometime this season.
For a real curve ball, I just thought of something. Everyone expects Jack to die in the last episode.
Instead, whenever Kiefer plans to leave the show, either this season or next, instead of killing Jack, him and Audrey simply go off together to escape all of the baggage of their former lives.
I don't think Mrs. Logan fits either. For one thing, why would get get into the limosine with the Russian leader and his wife? I was only being half-serious.
I still don't trust Audrey. I haven't trusted her from the beginning of last season. And maybe the apple doesn't fall too far away from the tree, either. But I liked Heller from last season, so I hope it isn't him. :)
i actually expect Jack to retire peacefully at the end of the last 24 show. why not? what would be the payoff in killing him? but i am an optimistic person for the most part.
I heard a funny one on Armstrong & Getty (Sacto) this morning: Jack would die at the end of the next episode, and they'd change the name of the show to "21."