If they won't kill Jack what more can they do? If they kill Jack the show is over. They've exhausted all the office moles and betrayals, extreme patriots that take wild measures to uphold their ideals. It's like Prison Break after they broke out of prison a show that outlived its own premise. 24 has been going on so long it just used up all the angles it could. There's nothing left to do at this point but retread the same path.
Hell this isn't even the first time Jack has been on the outs with the US government and had a foreign government out to get him. If this keeps on they'll just continue to reuse the same plot ideas they've already used. The one thing they could actually do is make Jack the bad guy ( I mean really a villain and not an extreme anti-hero) and have someone like Kate tasked to take him down.