While I was thinking about last night's episode I came up with this teory on the final scene of Lost. I'm probably wrong but, it's just a theory.
Flocke said that the candidates are people who may become the new protector of the island (the "new Jacob"). But Flocke doesn't think the island needs protecting, it's just a "damn island". This is very similar to a scene from a season four episode. Locke said that Jack would have to lie to protect the island. Jack said, "Its an island John, no one needs to protect it!"
I think that at some point Locke will come back to life, or maybe his was never dead (Medusa spiders, notice the spider that crawled off of Locke's body?). Also i think Flocke will be killed in some way (toward the end of the series).
With Jacob dead I think that Locke will become the new Jacob. And, somehow, Jack will become the new smoke monster (it's already being hinted that the smoke monster was originally a person).
The final scene will be Locke and Jack on the beach arguing about protecting the island, fate, free will etc. ( it was said that this season The Jack/Locke conflict will "come to a head"?) While they're arguing Jack turns to Locke and says:
"Do you have any idea how badly I want to kill you?"