In a world where George Lucas never lost control over his and two dead director's movies...
What would be the worst possible special edition changes George would probably actually make that you can imagine?
Here's my checklist:
Star Wars:
-Make there be twice or three times as many Jawas in the canyon, two thirds of them don't do anything but stand around
-New scene where Vader's TIE gets rescued by a Star Destroyer, all CG.
-CG new droids into the Lars homestead (why would they need so many droids?)
-New scene that shows the stormtroopers burning the homestead
-Establishing shots on Alderaan's surface before its destruction
Empire:
-Vader has a NoooOOOooo moment when the Millennium Falcon jumps to lightspeed.
-The Emperor outright states that Vader is Luke's father during the hologram scene, not a shred of mystery left.
-CG Yoda
-New scene of Boba delivering Han to CG Jabba
-New scene of DSII under construction
Jedi:
-Gungan added to Jabba's palace
-CG Yoda, Jabba, Rancor
-New scene of Boba escaping Sarlaac
-Jedi Rocks AND Lapti Nek
-Luke/Leia "sister" scene changed to remove references to their mother, or mangle together new dialogue describing in too much detail how she used the force to see Padme right before she died.
-Ghost scene shows Qui-Gon putting his hands on Anakin's shoulders and smiling to Yoda and Obi-Wan