I just watched the CinemaSins thing "sinning" the trailer, and the end contains several theories about Luke. The first of which being "He's Kylo Ren and Adam Driver is just stunt casting". Um, why won't this theory just die a horrible death? It literally makes no sense and the more I see it perpetuated the more I roll my eyes.
Luke might be evil. He might be a hermit. He might have legitimate reasons to be in hiding, and they're saving his reveal in the film for a very specific moment. But he's not Kylo Ren. Jeez.