We never had to argue all of this prophecy and balance/unbalance stuff before the prequels came out....just 2 bad mofos in charge of the Universe. Just sayin'. Let's imagine the prequels didn't happen. At the end of ROTJ, the 2 baddies were dead. Its implied there is no bad anymore. In the prequels this would be the definition of "balance". This is why I don't think there was another baddie. Forget the prophecy stuff, as far as I'm concerned that prophecy was just something Yoda and Mace cooked up while they were hot boxing their speeder.