I don’t know if we can say “beyond what JJ intended” since Abrams didn’t intend anything beyond The Force Awakens. He scrapped all plans, and was reading Johnson’s script while filming.
He should have either made Luke a full character in his film, or not included the scene on Ahch-To. Abrams chose to make his film a trailer, locking Johnson into writing a film that took place immediately after, unlike every other film in the franchise.