I feel like I've had this conversation a thousand times now and so I'm clarifying.

Luke Skywalker IS NOT and CAN NOT be Kylo Ren. An excerpt from the wiki:

"The individual who came to be known as Kylo Ren was born some time after the Battle of Endor. As an adult, approximately thirty years later, he had become a follower of the dark side of the Force and a member of the Knights of Ren, taking on Ren as a surname. He built his own lightsaber, a dangerous and ragged design unlike that of a typical lightsaber."

Some info on the Knights of Ren:

http://starwars.wikia.com/wiki/Knights_of_Ren

It mentions this bit of lore was created for this film. I feel like it's just that no one bothered to wiki his name.

I'm saying that. At some point Luke confronts a clone of himself made from the hand he left behind and wielding the lightsaber he lost there, though Disney might have relinquished that cannon also. It could even be an Anikan clone :P. Both of these would be cool but doubtful.