Well I thought for awhile that Jin's part might not be a flashback, but now I am pretty sure that it was.

Another clue is this:
When his taxi is taken by some guy Jin gets very upset and yells at the taxi something like "I'll rip your head off!!"

This is definitely something the old Jin would say.

so Jin must die on the island and the cover story has him dying in the plane crash, so thats why tombstone has 9-22-2004 for date of death.

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Doctor playing golf. Woo, boy howdy, now I've heard everything. What's next, cop eating a donut?