Here is what I want to first scene of Season 6 to be.
Flight 815 is in the air, and we see all the passengers we have grown to know and love. However, the plane hits turbulence, and the plane splits in mid-air, and the plane crashes in 3 pieces onto the Island, just like it always did, showing that whatever happened, did indeed happen.
Another possible opening scene that I would love to see is the crash of the Black Rock onto the Island.