Logan is not dead, as mentioned above. The fates of both Keeler and Wayne Palmer are still unknown, and it's unlikely they will be mentioned again.
It's true that apparently the FOX network refused to let the '24' writers kill a sitting US president. So Palmer and Keeler are in a weird limbo where they aren't quite alive or dead. They'll probably stay that way.
I'm looking for Wayne Palmer to return since we don't know what's happened to him. I think they could work him in to the resurrected CTU as working on the bureaucratic side maybe.