what if it wasnt a flash forward at all...Just kidding.....
i believe they are sworn to secrecy about the island in return for pardons etc...i say this cos kate is free and worry free despite the reason she was on th flight in first place.....all that trouble to arrest her, send her home...a plane crash would NOT allow her to walk free afte what she has done..Jack was tagged as hero and the others didnt like this - she wasnt happy to see him i felt

also thats is why she doesnt want to go back and jeopardise her future and the resaon Jack believes they need to go back...well....not a fricking clue i'm afraid...defo noe for lifestyle...maybe to save the island from the real world that are now experimenting onit?????????????