BZ, your claim is simply untrue. There were plenty of unanswered questions left after CT, and CC while following true to the original storyline simply left us with even more. There are plenty of options for Kato to choose on where to take the next game, if he doesn't pull another CC, answer some questions, and simply add a ton more =)
Lavos is indeed old news. There's nothing more Lavos could be milked for that makes sense. And Belthasar is a good guy, though a bit loony. He could indeed have the power to fuck up alot of things, but he seems to have the good of the universe in his mind. I'd like to see the Entity more involved in CB somehow, personally.
Oh, and Kefka was indeed strong before that Breaking the World stuff, but just not as God-like.