That sounds like absolute bullshit.
Unless JJ doesn't know what he is doing, and I doubt it, Luke CANNOT be anywhere else than where he was at the end of ROTJ. Just like King Arthur, Neo, Jesus, Captain America, Master Chief at the end of Halo 3, Luke can only be "frozen" until we see him again, meaning that when we will see him again he has to be the one we are most familiar with, the one that has the least been affected by the events of the time, but has become holier/divine. He is the connection between the audience and the original trilogy. The other characters can, but not Luke, he's from the template of the hero in the invisible land, waiting for the time to return. Or in SW's case, he's away to heal and not fall to the dark side, he wants to avoid becoming a threat to others.
So I won't believe anyone who claims Luke didn't just go away in isolation since ROTJ until it is officially confirmed. We have to be picked up right where we left him. Luke is not a "character", he is an archetype. If JJ doesn't get that, he's taking the wrong approach.
edit:
Sleeping Hero
So Luke is hiding somewhere, until the surrounding area changes or someone stumbles on him and he realizes things have changed for the worst and he must step out. He cannot be changed by events that have happened since we last saw him and his return since he is our vehicle to this new "era". We are supposed to be as much in the dark as he is.