i've been suggesting the whole sith-removal for a while now.

in the EU fiction sith rock as we have a whole load of backstory and they are presented as this massive super-culture. they really function in this context.

in the films however, they are a horribly simplified cohesive term for evil. this really really castrates everything about what anakin's turn should be about (which is one of the key themes of the series). the dark side/light side choice is something which we as people are presented with everyday, on a small level, and on a large level. luke's constant personal battles epitomize this. being consistently good, then becoming evil to join team-evil (ie the sith) doesn't seem to have that same personal relevance.

the chosen one prophecy is a bit cheesey IMHO buuuut could work well in the OT if it was mentioned in ROTJ or ESB. think of the "he was our last hope" conversation between yoda and obiwan. what if it is mentioned that luke is now believed to be the chosen one, as it is obviously not anakin. when luke is defeated by the emperor, and vader slays him, it would act as a sort of slight final twist. this overall though may detract from the theme of ROTJ, which is luke saving vader, as oppose to luke assassinating the emperor - that was just lucky.