Here are my three ideas for what the final scene of Lost will be:
1) As a parallel to the first scene of Season 1, the final scene will end with Jack closing his eye. This will likely be because in the last scene Jack will die.
2) As a parallel to the Others seeing 815 crash over the Island, the remaining Losties will see another plane, or other mode of transportation becoming marooned on the Island, thus solidifying their role as the "new Others". This will play into the whole history-repeating-itself theme.
3) My personal favorite: We have seen the Sydney airport, we have seen the Losties getting in line for the plane, we have seen them on the plane, we have seen them crash, and in my opinion, by the end of the first episode in Season 6 we will have seen the plane land in Los Angeles. The one thing we have not seen is the plan taking off. I think an amazing final scene will be everyone boarding the plane, and then, from the POV of outside the plane, we will see it take off in to the horizon, knowing full well what is in store for everyone on board.
Tell me what you think; leave comments!