I doubt it is Chloe, she has a good following, I doubt it is Palmer, Allstate wouldn't allow that. Might be the president character but I doubt that also. The current(as of last season) director of CTU since Sean Astin is going to replace him is a good candidate. The other one I am not sure.
I heard Sean Astin isn't going to run CTU, but rather will be sent "by the President" to oversee things at CTU. To me that means he will be there almost like Audrey was last year and will be this year, in an official capacity, but not in charge of CTU.
As for who gets killed, I'm sticking with Palmer. But backing off a little on Tony... nope. Sticking with Palmer and Tony. Final answer.
See Jan 9-15 issue of TV Guide, page 31 for update on who's new, who's back etc.