Something I was thinking about.
What if John Locke's spirit, soul, consciousness or whatever you wanna call it is still iside the body currently occupied by MIB?
We might have seen a clue about that with the don't tell me what I can't do line MIB said when he apparently lost his composure a few episodes ago.
He's also aware of Locke's thoughts at the time of his death...
Do you think there's a possibility that MIB might me driven out of his current body at some point in the season, and that our good old John Locke could make a return safe and sound in a brand new body?