Kuzan being alongside the rest is the most interesting development. I didn't assume his interests would eventually cross Teach's, but if he's being put as a main actor alongside his captain... Kinda get the feeling that he may leave the crew at some point, or outright betray it.
If this was another author, I'd bank on Kuzan trying to destroy the One Piece or something cool. Since it's Oda, his agenda is probably pretty mundane and forgettable.