I see Luke Skywalker as Obi-wan, not just for mentoring Rey to become a Jedi, but Luke Skywalker had the Original Trilogy, that was about him, just as the Prequels told the story of Anakin AND Obi-wan, so when it came to the OT, it wasn’t about Obi-wan anymore, he was in the trilogy, but only to mentor Luke, give him his father’s lightsaber and make way for the new characters like Luke, Han Solo and Leia to go on their adventure. He gave his life, so they could live.
The Sequel Trilogy is NOT about Luke, he has a job to do, that is to train Rey and reveal stuff to her, Leia and Ben Solo, just as Obi-wan did for Luke, Luke will do for Rey, but it’s not his story, his was told in the OT films. Luke will reveal things in TLJ that we already know and some things that we don’t. Will he give his life, so others may live as well? Will he live to Episode IX? That remains to be seen, but this trilogy is about Rey, Finn and Poe Dameron.
I liked TFA, but I hope Episode IX is not a rehash of ANY of the other Star Wars films.