Everyone expects Jack to die sooner or later so when it happens no one is going to be surprised.
Heck, with Michelle, Tony, and Palmer dead, that means there is no one left with ties to Seasons 1 or 2 except for Jack and Aaron.
Kiefer has said he thinks the show will survive without Jack but I don't think he realizes that it probably won't.
It actually is very interesting in that this is the essence of 24 and the heart of its appeal. The genius of the show is that we all know that the script will not take the usual routes that are on conventional TV and that it will surprise us, happily. The way it had the DOD chief slap down his son's empty anti-war rhetoric, "stop it with your 6th grade ideas" and the way Kate Warner' sister's rabid anti-americanism was portrayed out in its stark and empty finality. We saw it again with the sexual harrassment babe last night.
Contemporary media will not allow these portrayals onto the screen, but 24 puts them out there for us, out of the closet. The female leader who is destroyed by her stressed out family situation which will not stay at home[the CTU director last season whose daughter was a druggie who needed Mommy].
My first impression of 24 after watching only a short tome in season 4 was that this show was different and it would not fear to follow a character to his or her depths regardless of the identity politics platitude that was offended in the process.
All this is epitomized in Jack. He is like Keifer, exquiitively sensitive, yet in his skin so passionate about his mission that he will not stop at anything in order to do the right thing. The conviction of his rightnees always trumps the political correctness for Jack. He is actually not a single minded bully or zealot. He has a moral sense that is tested over and over and despite there being a lot of the comic book in his ultimate invincibility and coming out right in the end, it does serve as a tonic for the rest of us to see simple virtue represented as successful in at least one TV show.
In this sense, I do not see Jack as dying when the show "dies". That would be the wrong depiction of this character. He really should be immortal in the sense of surviving the last show so that he would be around in everyone's mental image and thereby available to be called upon, "one more time" when he is needed once again.