I don't think this is SPOILER material, since it has to do with one of the promos on the internet.
Many of you may have seen the "Numbers" promo running? There is a hybrid fan made/official viral promo on youtube. The link is here
So, the premise of the promo is Alvar Hanso telling us about the Valenzetti Equation. The equation derived to predict how long humanity has left on earth. The core values in the equation are the numbers used on LOST. 4-8-15-16-23-42. Now, there are 6 numbers and here we are in season 6!! There is a very important line in the promo that I think is very telling as to where we are going for the next and final chapter in LOST.
Alvar Hanso says, "Change the core values, and you can change the course of destiny."
Whether we are seeing an ALT timeline throughout the show, as some have suggested. Or whether we WILL see an ALT timeline as a result of Jughead, as others have suggested, I don't think it really matters.
What takes place on the island has always been the most important part of our plot. The values of the characters, the arcs that they have made through their experiences on the island are what I think they are referring to in the promo.
I think that there will be only six surviving members of our original Losties by the end of the show. That's why there are six numbers. Who they will be, I'm not sure. But there will only be six. Six people that both make an ultimate character arc AND survive.
I think that they will finally band together, our Losties, and they will lead the Others to battle whatever the ultimate villain is (be that Jacob or MIB).
But I'm going to say this. If Locke does not come back to life somehow, and finally get to reside on the island as it's eternal steward, becoming the new Richard Alpert, I will be crushed.