Lost: A story of Emprisonment and Redemption by Dharma Scientist

So it seems to me that the island is like a prison. You come here and serve your time, and if you are deemed rehabilitated then you can 'go'. That means you can die, like Michael, or take the place of Jacob or go back to your new improved life, probably in a parallel timeline. All of the Losties were prisoners in some way:

Jack: Prisoner of alcohol and pills, prisoner of his failed marriage, prisoner of his father, prisoner of leadership
Kate: Prisoner for killing her father, prisoner of her mother turning her in, prisoner of killing her friend tom
Sawyer: Prisoner of his parents murder/suicide, prisoner of anger, prisoner of his pain of losing loved ones in his life
Hurley: Prisoner of the numbers, prisoner of the curse, prisoner of his father leaving him at a young age, prisoner of lack of self confidence
Jin: Prisoner of his class standing, prisoner of his father-in-law, prisoner in his failure to communicate
Sun: Prisoner of a trapped marriage, prisoner of her loss of Jin, prisoner of her separation from Ji-Yeon
Locke: Prisoner of the wheelchair, prisoner of his failures, prisoner of people manipulating him, telling him what he can't do
Sayid: Prisoner of his torturer past, prisoner of losing every woman he loves, prisoner of being a killer

I could go on for a while, but you get what I'm going at. So it seems that if all the people are able to redeem themselves from their 'sentences' then they are fit to 'go'. This is where it seems like that the characters must die to go to the other timeline, where everything is good. Michael could go, he saved his son and saved many lives. Juliet could go, as she detonated the bomb to allow an 'in' to the other timeline. Sayid could go because he realized that he caused pain and suffering to many people, and was sorry for it. Locke could go, because he succeeded in helping his friends get back to the island to be saved and rehabilitated. So if a character is done with all their sentences, or discover a revelation, then they will die and go only to the other timeline. This is what worries me about some characters, as it seems like some characters are finishing their sentences, which makes me believe that they are going to get 'killed' or sent to the other timeline soon. The o! thers are perhaps people that haven't gotten their realization yet, their 'ah-ha' moment. I think that one of the prisoners/lostie must take on the mantle of spiritual guide, or warden perhaps, of the island, as Jacob. This way they can continue to save the world by saving the people in it, by helping them get over the chains that they carry with them, like Richard. It seems to me that MIB was brought here to serve his sentence, but never learned his lesson and so he stayed here on the island, never growing old. He then set about trying to find 'a loophole' so he didnt have to forgive himself and move on. I also think that the rules are that you cannot kill a prisoner that has not learned their lesson, finished their sentence, which is why Flocke can't kill Sawyer, why Ben and Widemore cant kill each other, and why in time travel people cant be killed, like Chang says. So ultimately, Lost is a story of people that have lost their way, and once they are Found, then they are ! free to go.