I think that when MIB fell into the waterfall, he unleashed a smoke monster. The whole time that we have been watching this, it was not MIB taking form of people, but an actual smoke monster. Noname is dead and that is the only explanation that I would be happy for. (Pretty selfish, I know). If that is not the case and there are no more flashbacks regarding Jacob and Noname then Across the Sea was pretty pointless.