Kate sees Claire.
Claire??? She will go back for Sawyer.
Aaron sees Claire.
I think this only because she has Aaron, and how exactly are they going to show a baby having a vision and wanting to go back to the island?? I'm not saying that Kate will go back FOR Claire, but that she have a vision of claire and that will make her go back to the island.
I kinda think them all seeing ghosts/visions is too predictable for Lost. I suspect they'll have different reasons. Perhaps Sun gets word that Jin is alive, for example.
I understand that, but sometimes, TV is too predictable. Take it from the big fat guy who has spent way, way, waaaaaaaaay too much of his life watching television. I'm not saying I can tell you the end of LOST, but things like this seem way too easy to predict.