Here are some rumours from Docarzt.
Because You Left" deals with several of the Oceanic Six coming to grips with their need to return to the island... on their own terms. If true, this means season five will get right down to it and do away with the issues of Jack 'convincing' Kate to return right off the bat.
In this sense the statement "Because You Left" deals with not a specific set of circumstances, but multiple character's circumstances.
Source: DocArzt