I think the Hutts would be really cool to see. I find it an interesting thought that they were so powerful as to be outside the jurisdiction of the Old and New Republics and the Empire. But I also like the idea of a cult surrounding the Vader persona.
I'd like to share my honest thoughts on the Light vs. Dark Side, and if they do go Jedi against Sith/Dark Jedi route, I hope they do this right. One thing that has driven me crazy in Star Wars from the PT, nearly all EU, fan lore, and even the OT, is that the Jedi are morons and the bad guys are always stronger. Yoda said that the Dark Side was "quicker, easier, more seductive," but not stronger. I feel this has seldom if ever been capitalized upon well (though I admit to not being as well versed in the EU anymore).
In an analogy to boxing, a fighter who gives in to rage and aggression can be quite powerful and intimidating, overpowering an unprepared adversary. But the fighter who is calm, controlled, and focused will triumph in spite of his less offensive strategy. The Force encompasses the spiritual as well as the physical, and I think the same applies, or at least should. But thus far we've yet to see much of it, and the good guys only seem to win on luck or when they succumb to the Dark. Anakin defeats Dooku and Ventriss in anger. Luke defeats Vader in anger. And otherwise the Jedi are defeated left and right by Force-less enemies (Grievous) or are too stupid and weak to stand up to Dark Side users effectively.
In my ideal ST, whatever evil is ultimately faced, I hope Luke faces it. And I hope that when he does, he does so as an absolute master: controlled, calm, at peace, and more powerful than any emotionally-driven enemy. To me that would show that the Light Side is truly stronger, and it would be a true victory for Light.
