I am a little concerned about jobbers like Luxord and Larxene returning, but ultimately I'm happy that certain characters get to be fleshed out a little bit more. I have a feeling that every seeker is going to get a ton of screen time, way more than the trailers may imply. Xigbar and Ansem meeting up to chat in Twilight Town really has me feeling like we're going to see a lot of seeker interaction, which is very cool.
Certain characters just need a canonical power-up if they're going to be a threat to Sora at all-- if Sora can beat up Larxene with only a handful of memories and remembered techniques, I have a hard time believing he's worried about her when he can whup ass with claws, yoyos, hammers, drills, guns, cannons, clones, a staff, ice skates, shields, olympic gauntlets, spears, and flags... It's Nomura's job to show us that these old enemies are now a force to be reckoned with.