With the recent post about Luke and The Light and the Dark. Also with Snoke mentioning Light & dark several times. It made me remember the rumors and concept artwork apparently that was supposed to be for TFA.
I remember a specific few where Rey was supposed to go and see Luke and find him guarding an ancient evil and talking to himself. Some of the photos showed Luke with a hood up on a high throne area ( reminiscent of all the Snoke on throne scenes now ). Also photos showing Rey looking into a mirror/vision and him standing behind here and then taking down his hood to show a half cyborg face Luke.
Did that concept art mean something there. I absolutely would not like to see Luke turn dark. Like others have said he could just be SPLIT. Don't think Hamill would be allowed to say either way for sure what Luke is or will be doing in this movie unless Disney said so. Hamill seems to be acting like what his character will be in this one and that being Split.
Really would not care for Luke acting like the Beast in SPLIT. Acting normal one minute then blasting Figrin Dan Cantina music and doing a crazy dance for Rey. Haha