Update: What the Hell was I talking about. This theory is totally ridiculous. I’ll keep it up as proof of my insanity.
This may not sound like much of a theory since all three of these characters have died in the show. But I propose that the three of them died at the end of season 2.
At the end of season two the Swan imploded with Eko, Charlie, Locke and Desmond inside of it. There was a considerable amount of mystery about what happened after that. It would have been easy to believe that all four of those characters had died, but then Charlie comes walking out of the jungle. In season 3 we concentrate so much on The Others that we forget what happened at the end of season 2.
After rewatching that finale episode I was reminded of the scene in season 4 when Sawyer finds Claire knocked out in the remains of her cabin. She gained consciousness quite quickly but she wasn’t the same after that. It became apparent that something was very wrong when she abandoned her baby to live with her father in Jacob’s cabin. Many people have suspected that she is dead, essentially a zombie. We have yet to see what happens to Claire after that point (apparently we won’t find out until season 6). But I think it’s a well spread theory that Claire is actually dead. This opens up the possibility for my theory.
I propose that the same thing happened to Eko, Charlie and Locke. They were killed in the hatch and the island, or possibly fate, kept them around. But fate did correct itself. All three of these characters have since died. All of those deaths have been pretty major and definite (with the exception of Locke, who’s death hasn’t totally bean revealed.)
You may be thinking, what about Desmond? Is he dead too? I doubt it, I’m sure that something happened to him but I doubt that he died in the same way that the other three did. Remember Eko, Charlie and Locke all showed up looking like they did right before the blast. Desmond, on the other hand, showed up naked. I’ll bet he was somehow reborn. But I still want to see more about Desmond to fully understand what happened to him.
This theory is an “Old Theory” simply because it’s irrelevant. All the characters could be “dead” it doesn’t really matter. It’s probably not correct though.