It has been said that the 9/12 SE discs are exactly the same as the '04 discs. One theory says that this all is partially an inventory reduction move. Maybe Lucasfilm/Fox way overproduced the '04 discs and need rid of them. I don't think there will be any further changes at this point. Perhaps for the next release, such as the rumored '07 super-duper-extra-special edition anniversary saga boxset.