You know, I complain a lot about Last Jedi and I was thinking what i'd do to change the film and the one thing that would of made it so much better. Don't have Luke Skywalker want to destroy the Jedi. Have him want to destroy the force itself. If he had to be this hermit, he needs a real reason other than "I'm a failed Jedi, time for the Jedi to end". Have Luke discover out in the far reaches of the galaxy some prophets who prove to him that the force is the cause for all wars. The reason why individuals like the Sith get so powerful in the first place and that the force doesn't always work for the Jedi or the "good guys" hence why Palpatine was able to overthrow the Jedi.

This means that Luke forged the map to the island in hopes that like minded individuals who had no affiliation to the Sith or the Jedi would find him using the map he left behind to discover his new methodology. Using the light and dark sides of the force in hopes to learn a ritual from the ancient Sith and Jedi teachings to destroy the force. This is why Kylo and Snoke oppose him and those protecting him (The resistance) as since all life is tied to the force, destroying it will kill everyone by extension.

Rey arrives on the island and after speaking with Luke, she is disgusted at his views but knows he is the last Jedi alive to teach her the ways of the Jedi, so she becomes his student only to learn the light side but during their time on the island training. She learns some of the dark side abilities as well, although she struggles with them much more than the light and doesn't get far in this training.

Luke later discovers from her force skype calls with Kylo that she is only using him leading to him using the force to destroy the building (That one scene we see in the actual movie) but now Rey has a reason to abandon Luke knowing her cover has been blown. She flees back to the falcon, using the force to augment her speed to get away from the stronger (but not faster) Luke.

She and the falcon escape the planet and return to the Crait. While the speeder attack on the first order forces scene is going on, have a skip back to Luke who is using the force to teleport himself to Crait. He arrives in the snow where Rey and Kylo were about to have a lightsaber battle but knowing the greater enemy, the duo team up one last time to defeat the rogue master. The two struggle and Luke gets to show off his many new amazing force powers while Kylo shows off what he has learned from Snoke's secret library of sith knowledge and Rey gets to use her new light and dark side powers she learned from Luke. The two struggle against Luke until Leia arrives on the battlefield and explains to Luke why his beliefs are wrong after Rey explains it.

Luke, in his care for his sister stands down only for Kylo to strike him down, much to the surprise of the audience. Leia rushes over to him and holds her brother in her arms, tears rolling down both their faces as Rey enraged leaps into battle against Kylo. A final goodbye between Luke and Leia before Luke dies in her arms and fades away (Obi-wan style). Leia yells at Ben to stop but he continues fighting Rey. Leia returns to the base where it is revealed by Poe that Luke upon his teleportation opened the blocked passageway (The one that Rey uses the force to open in the real movie) and the resistance begins to leave. Finn says to Leia that they can't just leave Rey as they see Rey get knocked out by Kylo and brought (alive) aboard Kylo's Walker.

Supreme Leader Kylo tells his forces to let the Falcon go stating they will come back for the girl and when they do, the resistance will be fighting on the Order's territory. Ending scene of the resistance aboard the falcon (like in the film) meeting up with newfound allies (Lando Calarissian maybe) who agree to help against the First Order, setting up Episode 9.

Post credit scene of Luke's ghost on Ahk-to with Anakin, Obi-wan and Yoda's ghosts discussing Luke's mistakes but saying that the girl is now the galaxy's last hope if she can get away or turn Kylo back to the light.