What if, instead of the flashsideways, we got even MORE Island flashbacks, and better explanations as to the events on the Island.
Read up on Chott El Jerid, its a huge (Island-sized) depression in the middle of the desert in Tunisia, directly next to where Ben checked in at the hotel after he warped off the Island. Tunisia is also a few hundred miles from Egypt, where we know the Island definitely has some ties.
Now imagine there was an episode simply titled "Prologue". It tells the story of an oppressive Egyptian Pharoah who sends a group of slaves to Tunisia, where he hopes to extend his kingdom from Egypt. There, in Chott el-Jerid, the slaves discover a huge energy source underground while they are building a pyramid.
The Pharoah hears of this discovery and travels to Chott el-Jerid to harness this discovery for his own use. Meanwhile, the slaves discover that this energy is actually holding back the gateway to the Underworld, where demonic forces have slowly begun to seize the souls of the slaves.
The slaves were not allowed to have names, they had instead been assigned numbers by the Egyptians. When the Pharoah arrives, he finds that only slaves Number 4, 15, 16, 23, and 42 have survived. They beg him to get away from the gateway and never to open it again, but the Pharoah is blinded by his greed.
He instead uses the 6 slaves as bait and plans to throw them into the energy source to see what happens when humans harness the powers. A battle ensues when the slaves revolt against the Pharoah, but in the end, the Pharoah manages to harness the energy and become immortal, feeding off of the energy of the dead.
One of the slaves tricks the Pharoah and throws the Pharoah into a fire, where the Pharoah burns into a cloud of smoke, forever trapped feeding off of the souls of the dead from the Underworld. The Pharoah Smoke Monster then tries to open the gateway to the Underworld to achieve unlimited power.
To stop him, the 6 slaves, numbers 4, 15, 16, 23, and 42, decide to give their lives by merging with the energy. This huge sacrifice causes the surrounding land to simply shift out of time and space, thus the giant depression of land in the ground in Tunisia.
The souls of Slaves 4, 15, 16, 23, and 42 are forever tied to the destiny of the Island, and prophecy foretells the day when their reincarnations would return to defend and protect the Gateway from ever being opened ever again.
LOST