i voted for "he may have had an inkling"
i don't think he definatly knew anything was going to happen to boone simply because i don;t think even locke would have gone so far as to let someone die just because of "destiny" or whatever.
i didn't say he had no idea though because we know from further instructions that locke see's the island as something to talk to, and the vision could have been the island talking to him, telling him what was needed. Also the way he said, after boone had died "he was a sacrifice the island demanded", this does make me think that maybe he did know what was going to happen
