Dying to Live by Layla

Those are my basic thoughts for the finale:

1.Desmond will be shifting between the two time lines till he realizes what's happening with him as he interacts with more losties in the ALT time line.

2.This realization is the trigger to converge the two time lines as they found their common factor (Desmond).

3.As we have seen before whenever someone dies on the island his subconscious unites with his body in the ALT time line.( In other words ," REINCARNATION "we have noticed how many times the producers used the reincarnation theme in many episodes).

4.So in order for the losties to live the life they chose to live THEY HAVE TO DIE ON THE ISLAND. In fact, I think dying is their salvation. Therefore when the losties die on the island the two time lines will converge and become one .Otherwise, if they survive and left the island in a plane or a submarine, the island will end up bringing them back somehow.(Remember Ben telling Frank "that the island got him eventually") .

When Isabella said we'll always be together she meant when she died her subconscious united with the ALT time line where she is living with Richard happily and maybe she didn’t get sick and pushed Richard to kill that man. We have seen Juliet staying on the island just to get her sister cured, I am thinking maybe what we've seen on the screen when Ben proves that Jacob cured her sister was not the same time line ,I believe it was the ALT time line were people are having different lives. Jacob knew about the AlT time line, therefore he pushed them in the island time line to come to the island and do his things knowing they are having the life they have chosen in a different time line.
So Whoever dies on the island gets to live the life he has chosen on the ALT and I am assuming the island will be destroyed or vanished on the island time line because it existed only for a period of time before it submerged in the ALT time line.
5.As for smoky and Jacob I agree with the Jacob and Esau theory. Yes, they are brothers and their mother preferred Jacob to Esau creating the ultimate rivalry. They lived there since the Egyptian time. Even Jacob's love for tapestry is either an Egyptian cultural activity he kept doing or maybe his mother used to love it.(Remember the hieroglyphs of smoky confronting the god Anubis on Cerberus Chamber)Indicating that their rivalry was AB AETERNO .

6.So Maybe the mother made Jacob the leader of this magical island leaving Esau with nothing but hate or envy .Then Jacob captivated Esau and took away his humanity or his human form ( that's why he didn’t die or even bleed when Sayid stabbed him with a dagger ) which turned him into a soul with no physical body ,trying to reincarnate through any dead body or taking the form of a memory of someone the losties cared about just to set himself free .

7. Jacob wants to protect the island because he has always known how important this place was (being located on a spot with the highest amount of energy on earth ).

8.The island needs to be protected from any kind of harm or abuse by certain candidates (Jacob knew the relation between the island and the valenzetti equation which has certain NUMBERS).

9.He set the lighthouse at certain coordinates based on those numbers to find those candidates and push them toward the island. The numbers of the valenzetti equation represent the last candidates as Jacob called them, meaning he used to bring people before the valenzetti equation was proved and when it was proved he knew who were the last ones to bring before the end of the world.

10.Apprently smoky doesn't care about the END Of The World he just want to go back to his ERA before anyone takes Jacob's place and prevents him from leaving.