Eh. I don’t think I’d want them to go overboard with guest characters in a potential sequel; that’s what I find annoying about Netherrealm games. I’d say 2-4 max is good. Personally, ideally the only guest would be Doomguy since he really fits, and they could save the rest of the budget for new characters. KI ‘13s roster is already great, but they could try doing a frankenstein type character or a creature from the black lagoon character, or something else more original.