I don't know if you know this but Lucas isn't making 7,8,9. The WHOLE story is that it revolves around Anakin. His innocence and power potential, his fall from grace and his redemption. And Lucas did say that Anakin is the chosen one, not Luke.
But like all the Jedi are to be killed. W/ the exception of a few of course. Obi Wan and Yoda. So weather or not we see all these other Jedi get killed, i guess it's safe to assume. "...Now the Jedi are all but extinct."- Obi Wan in EP IV explaining to Luke about his father and Vader. That whole scene there is awsome.
Anakin was discovered by Qui Gonn. Qui Gonn saw something in him that the others didn't see or want to deal w/ becouse the Counsell thought he was old. He was refered to the chosen one to bring balance to the force. Think about it for a second. There are something like 10,000 Jedi in the whole galexy as said in EP I book. There are no more than 2 Sith at a time couse they killed eachother off for power and the Jedi killed off what were left. But we know that's wrong.
Anyway, the balance of power is this- 2 Sith at one time and all these Jedi. Here's the Chose one. He eventually goes DARK becouse of he was seduced by the DARKSIDE. In that, the Jedi scourge begins w/ Anakin and now all the power that was once the Old Republic that becomes the Empire goes after the Jedi and all that support them making them the start of the Rebellion.
Messed up it is. But it makes sence. Seeing how it all goes down tho will speak louder than this talk here. Even Sam Jackson talked briefly about his demise. I think that Anakin will get him. The looks that Anakin gave him in EPI when Windu said he won't be trained. But i could be looking to much into that. Who knows.
Well i hope i didn't bore ya by talkin too much here couse now i need to shut my comp. down for a bit. I have a brain cramp ! Later