Ninja/Green Mage both seem like they have enough potential to be full classes on their own, but if it makes it easier to get them turned into full classes I wouldn't mind hybrid. I'd have to dig around to find some other stuff though. Also could be archetypes that could be expanded into being hybrids.
Edit: Looking into it, Ninja looks like you could emulate it with Thief/Monk decently well.
Edit: Looking into it, Ninja looks like you could emulate it with Thief/Monk decently well.