So I've been developing a theory as to the true nature of the show and what the main plot of the last season will be while re-watching past episodes. Some of this might sound a little familiar since some of these ideas have been explored already but here me out. I believe that the island is essentially a big complicated game board for which Jacob and him nemesis play out their feud by manipulating people to be used as their game pieces. Someone already pointed out that there always seems to be essentially two sides in conflict with each other at any particular time on the island. Bram also mentions that he and his accomplices are on the "side that's going to win".The phrase "the island is not done with you yet" has been uttered and many people either can't seem to get away or are extremely compelled to be there. This is the way that I believe that Jacob and his nemesis set the board to start the game.
You may also notice that many people have similar traits and skill sets. This was shown in part by the episode "He's our you" in which there are two torturers. There are also many other people with similar skills such as tracking, hunting, leading, and being resistant to the effects of time paradox. Despite the fact Jacob was seemingly killed during the season finale, I believe that the conflict is not truly over yet. Since time travel is such a big component and the fact that Jacob was not very resistant to being killed, I believe that he already has a backup plan in motion that will bring him back or prevent his death.
I also believe that Miles will play a big part in the coming season seeing as how Jacob's nemesis can take on the images of the deceased. Miles' unique ability to hear things from the dead is probably the one thing that will help people reveal when someone is actually Jacob's nemesis in disguise.
I also have another theory about the manner in which Jacob and his nemesis control their "game pieces". It's obvious that Jacob's nemesis uses images of dead people to manipulate people into doing things but so far it's unclear if Jacob is also manipulating people and if he is by what method. I'm wondering if Jacob might be manipulating people through their dreams. Don't quote me on that one though. So far I've been trying to determine if it seems like people's dreams are in conflict with what dead people are telling them to do as I'm re-watching but nothing seems certain yet.
Anywho, I'll stop boring y'all with the ravings of my disturbed mind. Let me know what you think.