I always hated how comic books could never stay consistent. No major character has ever stayed dead permanently, no problem has ever been left completely fixed, and because of this it just kind of ruins the satisfaction of each of the next entries because you know this is true. Something else will happen. That's why I think the Sequel Trilogy should take an entirely new direction.
Star wars has always been about the people, and the decisions they make between each other. That's its main draw. I don't want this to go down the repetitive drain just like so many comic books and never ending franchises (like James Bond, for example) have. I don't want the force to inevitably cycle in and out of balance just for the sake of more movies. They can think of more than this. Star Wars is a big universe.
The most interesting way I have thought of to keep this intact is something akin to Gurren Lagann, or Mass Effect. Its a very, very awesome type of plot and has the potential to raise infinite moral questions about who we are and what we stand for. A threat infinitely powerful makes its way the galaxy and wishes to wipe out all biological life for the sake of saving the universe from eventually plunging into chaos. Remember, the force is still in tact. Everything Anakin and Luke has done is still significant and meaningful. But this time, the threat isn't even biological or native to the galaxy. The entire galaxy must fight together, and while working to get along must inevitably solve political problems and agreements, to eliminate this threat. This process is where the beauty of what makes star wars can really shine. Because you see, its not about the impending foreign threat Luke, or whoever the protagonist is must face, the trilogy must focus on how they fix it together.
What do you think? Its just an idea, of course it probably wont happen. But again I love this type of story line because it can raise so many questions and really blur the line between what is good and evil. It could really provide a nice shake up for the star wars franchise while still staying true to the source material. And keeping what everyone has done in the previous movies meaningful as well.