I think there are three reasons why the losties are not dead: Richard Alpert, Juliet, and Ethan. These three are seen off the island in Juliet's FB. Ethan and Richard bring Juliet to the island. So can't we say that they are all alive in Juliet's FB? In later episodes they each have dealings with the losties, so what are they ghostwhispers? And does that mean a dead Charlie killed a living Ethan?
Then looking at a slightly different way, if all the losties are dead, does that mean all the others are dead too? So then ghost Richard and ghost Ethan go and recruit very alive Juliet?
Then what about Naomi, if they are all dead, then does that mean Naomi is dead too and didn't really survive the tree landing?

If they are all dead then things just don't add up. IMO anyways.

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Doctor playing golf. Woo, boy howdy, now I've heard everything. What's next, cop eating a donut?