The Island Never Reappeared After Ben Left It by The Goatman

The Island never reappeared post Oceanic 6 and always sank after the Incident. The Island is still in some nether world that can only be reached periodically. The sinking of the Island had a huge effect on those who were on the island before the sinking. But it didn't register with any of those who were on the island that caused the sinking. They are living out their lives with no knowledge of their collective past.

All of those in the flash sideways who were on the island have had their past lives reset. The island sank and everybody was evacuated in 1977. But, that was caused for some unknown reason by instability with the Island itself. Dharma or the Others never met any of these people. That isn't the end of it. The Lost time line is now engaged in a struggle with the supernatural forces at work on the Island.