OK, the question is a heresy ... Star Wars is one of the greatest films of all time, and you just don't go remaking TGFOAT. Like The Godfather, or The Sound of Music, or Ferris Bueller's Day Off
But, hear me on this ...
It has been mentioned around the scene that the sabre duelling in the Prequels makes the sabre duelling in the Original Trilogy look a little lame. Any number of spaceship scenes, both exterior and interior shots (I am thinking of the Slave I cockpit shots in ATOC), make the Millenium Falcon cockpit scenes of the first two movies look pretty wooden. A number of small things are creeping into the story which have caused people to question the continuity of the plot (the droids' pre-knowledge of Tatooine, Obi-Wan's preknowledge of the Death Star, the OT absence from the Jedi Astral Plane of Qui-Gon Jinn).
After the Prequel Trilogy is done and done, some years from now (more than ten, probably), George will decide that the plot-tweaking he did has made necessary a re-rendering of Episodes IV-VI. We won't have Mark Hamill, Harrison Ford, Carrie Fisher and Alec Guinness, but we will have the technology to put their images into revised scenes. In short, the OT could be remade to mesh more neatly with the story arc from Episodes I-III. Older fans will no doubt be outraged, but a whole new generation of kids and teenagers will love it.