For the PT, only things that go back to the backstory Lucas had in 83 are worth keeping. There's no point in trying to keep specific performances from the PT, because we're talking about remaking the PT. The only performances from the PT I consider good enough are Liam Neeson's performance and Portman's TPM performance. But remakes would probably be using different actors, certainly different performances. The PT storyline should be cut back to things that were in Lucas's old notes or are known to have been in the backstory back in 83 or that seem obvious. That way we'd stick as close as possible to the backstory that was behind the OOT. Anakin would be an adult or so when he meets Kenobi and would be in his forties or so when his children are born. Kenobi would be in his fifties at the time. There'd be no Jar Jar or or Grievous, probably no Jango. No Qui Gon or Dooku. The Jedi wouldn't be such wankers. Kenobi would decide out of arrogance that he could train Anakin as well as Yoda and he'd screw up. Anakin's wife wouldn't die until Leia was a few years old. Owen Lars would be Ben's brother (as decided by Lucas during the making of ROTJ).

I don't think a sequel trilogy should be made. If it was, I'm not sure the EU material is good enough to base it on. In a sequel trilogy, under no condition should actors other than the originals be used for the major Star Wars characters.