Originally my idea for the Sequel Trilogy standalone, what I was thinking of calling Once Upon a Time in the Galaxy, was sort of meant to be a spiritual sequel to Pulp Empire. At the time snooker was working on her own Tarantino-inspired prequel standalone, Destroy All Jedi, which inspired me to think about it. I had the idea that all three could’ve been a loose trilogy of 3-in-1’s for the Saga.
For this idea of Prologue/Epilogue, I really wanted to make edits that supplement the original trilogy, which is Luke’s story, so really these bookends are meant to depict the birth and death of Luke, while the OT depicts his life. Also, I think this format would harken back to the serials that originally inspired George. The Prologue would actually begin in medias res, starting right in the middle of the war. And the Epilogue would end as a new war is beginning. There’s no real beginning or end to the serial, but instead it is a series of endless adventures on countless Saturday mornings.
I think it would be challenging to jump between the prequels and the sequels as one movie in a cohesive way. The only think I could think of would be to have the movie use Luke & Rey’s segment of The Last Jedi as the frame story, and when Luke tells Rey about Darth Sidious and creation of Darth Vader, you could fade into an extended flashback sequence where we see what happened. You could just make a 30-minute version of Revenge of the Sith and we could see how it all went down.
But your idea for a 6-in-1 and idea Eddie Dean had earlier has gotten me thinking. You could even expand on that idea a little and have flashbacks throughout the film where relevant. It could open with a flashback, like Eddie Dean suggested, but then when Rey hands him the lightsaber, we could flashback to when Obi-Wan gave Luke that lightsaber so many years ago. There would be quite a few good opportunities to insert flashbacks from the entire saga. Like when Luke sneaks aboard the Falcon, Luke could remember some of their adventures aboard the ship. Like I said earlier, when Luke tells the the story of the Republic falling, we could flash back to the prequels. You could essentially make an 9-in-1, with the Luke/Rey segment of TLJ as the frame story.