Jacob and the Nemesis, My theory/questions.

First point, is about Jacob, he can’t be dead (Think of all the hundreds of years he has lived on the Island, Ben couldn’t of been the first person ever to kill him or to try at least). If Jacob is dead, is the reason he wanted Hurley on the Island is to communicate to his people through him, to make him the new leader?

Now that’s said I want to talk about his nemesis. Presuming this whole time that his nemesis was the smoke monster and now he is pretending to be John Locke. Since smokie told Ben not to kill Locke and if Locke was killed in his present form would smokie die too?