"Locke is next to crossover"
Do you mean as in die or become an other? I think at this point Locke holds so much information about the hatch that they can't kill him off without another lostie getting a brain dump. But if you mean he'll be next to become an "other" hmmm...if so, I see it more down the line perhaps season 3 when Locke gets taken by the black smoke again and is actually pulled into the ground as he was originally meant to be.