I agree that this ending might happen, but I think it'll be in Locke's head. He's the character with the most difference between his "real life" persona, and who he is on the island. He also seemed to be near omniscient even before he became the smoke monster. There were lots of indicators of the dichotomy happening in Locke, the black and white chess pieces, Claire's dream where Locke had one white and one black eye, etc etc. One could argue that these are symbols of the battle between good and evil, but what if its the battle between reality and fantasy in Locke's mind?