From E! :

Carlton Cuse revealed: We aren't changing any of the format of the show. We are just adding the flash forwards as an element. They have made a radio call to a freighter, and there are people on that freighter, and it might be logical to imagine that that storyline will continue... The situation is going to be very intense this year. Charlie wrote on his hand not Penny's boat , and the message he wrote on his hand was very important. It was really funny because the clip at Comic-Con showed Mr. Friendly saying, 'by the time you see this, I'm gonna be dead, but I am telling you it's a shame because whoever is going to come after the Others is going to be a hell of a lot worse than we ever were.' Damon and I were listening to him and sort of nodding our head going, 'That's pretty prophetic.' With Jin and Sun there is a very dynamic situation at work. She's pregnant... the fate of her child, the fate of their marriage, all those questions Damon and I will get to and more this season. Walt will be back. You will see more of Jacob.