It sounds too much like they would be dragging up some ancient Sith baddie / artifact / weapon ... which nobody (except perhaps diehard fans) has ever heard of. Which doesn't really make any sense and is rather silly. I still firmly believe they should be leaving the "Saga" as it is with everone living "happily ever after" at the end of Return of the Jedi.
I'm not really sure what it says when someone admits that their movie will likely be considered boring and then does very little to eliminate the boring parts. There's many cool things in Episode I, but there's a lot of 'corny' and a lot of 'boring'.George Lucas did say that the start of the story would likely be considered boring, which is why he started in the middle.
It seems like a core part of the story should involve Luke training more Jedi. I know there's EU books about the subject that I've never read. In any case, it seems like there'd probably be a bad apple or two in any group that he attempts to train (and I doubt he's a great teacher anyway). It wouldn't necessarily have to be their children. Although another angle would be that Luke and Leia go to great lengths to suppress the truth about Anakin ... which makes the story of Anakin more appealing to their children (and perhaps takes them down a similar path).It's set 30 years later, so the New Republic will already have been up and running for a long time (barring possibly a few long-term hold-out Empire planets / hideouts). The only real sensible option for a third trilogy is if one of Luke or Leia's children "does a Dooku" by rejecting the Jedi and turning Sith ... but even then it doesn't make a lot of sense, unless they're planning the third trilogy as the rise and then a fourth trilogy to defeat the new Sith. Which would basically just be rehashing what the six movie Saga has already done anyway (but then re-hashing old ideas is almost all that Hollyweird is able to do these days ).
Darth Plagueis discovered how to cheat death. I suppose he could still be around.Darth Plagueis ... I wouldn't be surprised if they make a prequel-prequel trilogy (Episode -1??) about Plagueis and a younger Palpatine.