the only reason I support the whole "Anakin tuckered the old fart" theory is because its in the scene descriptions in the screenplay and it was in the novelization, which, for that scene, was pretty much word for word from the script. I know the authors are allowed to fill in were needed, but its seems Lucas made a point to show it.
well the way i see it is that yoda has to get old and sickly pretty darn quickly for starwars 5, so i think something will have to happen to him in starwars 3 maybe a fight between sidious and yoda, so i dont think he will kill dooku so id bet on obi anakin, as obiwan beat maul, and mace windu would have to die, and other than anakin ive ran out of jedi? i cant see how lucas can fit all this into three hours, i hope it doesnt come in two parts like kill bill.
yoda doesn't have to get sickly. here, for everyone who doesn't seem to get this point:
to kill either Vader or Sidious, Yoda (or Obi-wan) would have to march right into either A) the death star (one or two depending on when you think Yoda should have fought the Empire) B) Coruscant (who's main city is now called IMPERIAL CENTER, ie-loyalist central) or onto a Star Destroyer. How could either one of them, or even both together, walk right into any of those places and live? As we all clearly saw at Geonosis, the Jedi CAN be overwhelmed and taken by surprise when they're pushing they're powers to their limits. Yoda didn't fight in during old trilogy (or at all against the Empire) because their was no way he was gonna get close enough to do any good. And he was sickly then, hence his death in ROTJ and the line "sick have I become" but none of that really matters. If you've heard the newest spoilers, you'll clearly see the Jedi are kinda f-ed over, like we didn't know it was coming anyway. But without proper reinforcements, no Jedi will ever defeat an army, ESPECIALLY the Imperial military.
"We can only protect you, we can't fight a war for you"-Qui-gon Jinn
Remember how well Qui and Obi did in the Trade Fed Battle cruiser in epI? Now imagine thats a highly trained Imperial army rather than a bunch of mindless droids. Instant bloodbath. There was no possible way for the Jedi to stop Palpatine DURING his rise to power and even less of a chance once he was firmly in charge of the biggest army the galaxy had ever seen. So he doesn't have to go through anything traumatic to not go against the Empire. He knew there was no way to go against them, both at his age and because he didn't have any back up to speak of.