I think JJ lacks the care factor to shit on 8 by rezzing Luke, but he'll have him around in ghost form with respectable dialogue and possibly participate in an intervention of some kind. His hurdle is that Luke has been "killed" not just in the movie, but his actual character was assassinated from this timeline forward. No one wants to see a post-episode 8 Luke. Any attempt at Luke fan fare in 9 could easily amount to Jar Jar Luke stuff.
He has banged heads at Lucas Film to force the committee to accept his storylines before-- so anything is possible. Rian on the other hand, said he didn't have to bang any heads to get his story approved. Maybe their bell was still rung by JJ and they were unconscious while Rian pitched his Episode 8 ideas. What else makes sense?
With the force powers being homogenized, and whimsically supernatural, its sort of "anything goes" as far as plot. So I could really give a fuck less what JJ comes up with. Its just another DCU Marvel movie franchise now when any Jedi is involved-- we can seek refuge in the anthology movies where hopefully Jedi do not exist. Solo, Fett and so forth.
And if Disney's plan is to not offer George Lucas the Obi Wan movie, they are REALLY shooting themselves in the foot. Its the only way to quell the backlash and get PT/OT folks to stomach the idea of Jedi again. If the offer is made I just hope George is receptive.