Bosses have plenty of room in their bitfields... I could see a Trigger field, and if it's non-zero killing it activates that trigger instead of ending the level. Like most any other game. (Or there could be an additional bit used for a Miniboss flag and THEN the 0-31 trigger, but that's silly, and trigger zone already doesn't work with 0, so I don't think people would mind too much.) I think this would make for a lot of really interesting design possibilities, but I'm biased towards anything JJ2+ could do that would benefit single player, so...