I know I've said it before (and recently), but I kind of wish that they'd take up Hiro right up where the last story implicitly left him*: as a robot. If that's not a situation ripe for some form of the "rebellious AI" theme, I don't know what is.
I might be the only one who thinks that having one Toyman who's also a toy in a sense would be kind of fitting, in a way.