if I may...your idea is a fantastic one. But you'd have to be able to build your own charachter. During the game you would choose the alignment of both revan and the exile through conversations. then, depending on your choices, you could destroy reven with the exiles help, you could destroy the exile with revans help. you could save both, or destroy both ect.
but I like your idea, bringning back the original cast, and...posibly, merging with the newer cast. have bastilla and carth come back (maybe mission) and, with the handmaiden, mira or hanharr, and HK-47's help, do the story.
This is a great idea. I love it, and it could be made to work.
you could even re-visit the previous planets, in an attempt to find revan and the exile.