LAST EDITED ON 05-25-10 AT 10:05 PM (EST)
Those answers, really?
"is it real to you because you think it?"
This is fiction so no, it isn't real to me.
We know MIB wanted his humanity back, that he prefered to walk because it reminded him he once had a body. He wasn't going to leave the island any other way but as a human.
Locke needed to turn off the light and, when it went out, he stopped being Smokey. Knowing how Jacob and MIB kept making pacts, I think it's a safe guess that his metamorphosis was all part of a pact. Since that hole looked like the fires of hell, who else would make a pact to open it up?
ETA: MIB wanting to leave as a Human being would also explain a question that many asked: How could Smokey have appeared as Christian Shepard in LA? As one of Smokey's representations, I'd say Smokey could leave the island but that wasn't what MIB wanted. He wanted to leave as a human being. The only way for that to happen was by getting the light go out so Jacob couldn't let him leave.
BTW, I don't care at all what a writer that left the show years ago has to say about it now. He left either because he had a better offer, because he didn't give a damn anymore or for professional differences. I only care about what is on the screen.