The O6 Going Back
In Because You Left, Ben and Jack share this little conversation which I find slightly odd:
BEN: Did he tell you what happened to them after the Island moved?
JACK: No. No, he didn’t.
BEN: Then I guess we’ll never know.
What is odd is what Ben says when he says they’ll never know.
The O6 seem to have to go back to the island to save Sawyer, Juliet etc. from dieing. Jack said that Locke had told him that everyone would die if they didn’t go back.
So, assuming they go back to save everyone from dieing, won’t Sawyer, Juliet etc. tell Jack what had happened to them?
Unless, if you take what Ben said to mean that everyone is already dead then they “will never know“.
But still, if they’re dead, what is the point of the O6 going back to the island?
I know some theories have said that the O6 go back in time when they get back to the island, and based on this conversation I agree that they do go back in time, however Sawyer, Juliet etc. will have no recollection of their time jumping.
Which is why Ben says “I guess we’ll never know”.