Things I would keep:
"A long time ago in a galaxy far far away..." except shifting to an entirely new area of that galaxy.
Jedi Knights - maybe. Except that they would be different from the lightsaber wielding, limb slicing, bumper sticker wisdom quoting Jedi we're all too familiar with. More evolved, different weapons (if any) and not central to the story, more or less in the periphery of a much larger story that's not about the Jedi or any of the overblown nonsense associated with the Jedi, like temples and texts and - oh God...padawans - that were tacked on to the later movies. The Jedi were portrayed perfectly in the first trilogy (SW, ESB, ROJ) and that pretty much covered the Jedi story. After that the whole Jedi thing just went into massive overkill. But I would probably have something Jedi in new films at some point just to set the stage that it's a Star Wars movie and not another Marvel superhero movie in space.
As Lucas frequently mentions, Star Wars was inspired in large part by the serial movies of the 40's and 50's. The opening crawl, the stylized screen wipes and transitions from one scene to another, the over the top heroics and bravado of the main characters, the cliffhanger ending in ESB...all of that was lifted directly from the old serial movies. Lucas just bought it all to a more modern age and updated the techniques. And all of the SW movies that followed SW, ESB, ROJ seem to have forgotten that. So I think Disney needs to get back to that original vision for the first SW film because there's nothing wrong with a SW film that's simply fun and entertaining to watch like SW was when it was originally released, and without the need to figure out stuff like what's up with those Jedi texts and all of that other stupid nonsense we have now.