I have always wanted there to be a third trilogy because I want to see Luke Skywalker as an Obi-Wan/Yoda Type Jedi Master passing on the torch to a new generation of Jedi Knights and to see the Republic rebuilt.
There has been novels about that but I want to see that in films.
Mark Hamill has said that Lucas asked him to play an Obi-Wan type character in Episodes VII-IX and that it would be made around 2011.
There has been another rumor of there being Episodes 7-9 on TheForce.Net this week. I hope it's true.
I think the SW saga should end with Luke passing on the torch to a new order of Jedi and not just a celebration around the galaxy. And I think Luke's prophecy was training a new order of Jedi Knights to defend the galaxy and being them back to their former glory.
I still do hope there will be a sequel trilogy set either 50 or 100 after Return of the Jedi with Hamill as an 70 or 120-year old Luke and Luke's son Ben Skywalker and his grandson as the heroes of the sequels.
I think the Legacy of the Force book series or post-Legacy of the Force(the era set between LOTF and the Legacy comic book series would make a perfect sequel trilogy and it could deal with Jacen Solo as the next Sith Lord since he is becoming the next Darth in the upcoming SW novel Legacy of the Force:Sacrifice.