The Smoke Monster is John Locke
Sorry if someone’s already talked about this, but I haven’t seen anyone mention it yet. I believe the “new” John Locke is actually the smoke monster. You know when Ben fell down into the ruins, and was left alone with the Monster? Well, why is it that this newly reborn Locke and the Monster haven’t been seen on screen together? Because Locke never did come back to life (as Ben said nobody can come back to life), and that the Monster just took his form. This might also answer what’s in the metal box that the people from the plane are trying to open. It might contain Locke’s coffin and real body!!!