OK, if the best spoilers in circulation are true, it goes like this:
Anakin kills Dooku
Obi-Wan kills Grevious
Anakin kills Mace
Palpatine defeats Yoda
Anakin kills little Jedi kids
Obi-Wan defeats Anakin
Vader appears some time after all this. It is indeterminate if he'll fight.
The only thing that really irks me is that Yoda looses to Palpatine? Dude! Yoda is the man! Nobody can beat Yoda!
So Palpatine hands Yoda his butt, and then Anakin (as a crippled Vader) defeats Palpatine? What? How? Why? Because Vader wasn't biological? The Emperor's lightning didn't have as great of effects on him? If the Emperor was so physically powerful, (to defeat Yoda in a duel) why didn't he just wriggle his way free of Vader? Instead, he shoots lightning but otherwise doesn't appear to struggle that much. Did he create the instrument of his doom (Vader) ? What's the message here?