So I was thinking...

[B-Wing]

I was under the impression that the only way for factions to re-emerge in M2TW is if they are set to "never die", which was an attribute only intended for the Papacy. The way it worked in MTW (if I understand correctly) is as follows: If a faction is destroyed whilst its family tree contains an heir who has not yet come of age, there's a good chance that once he does come of age, he will appear with an army carrying his previously deceased faction's banner. I'm not sure exactly how this differs from M2TW, but considering that the Papal States faction has no family tree (or does it?), I don't think it has anything to do with heirs. I've never actually played a campaign in which the Papacy was destroyed, so I can't really speak from any experience.

Oh, and my main point here is that, the way I understand things, in order for a faction to be able to re-emerge in M2TW, they must be set to "never die". Problem with that is that rather than having a situation where a recently destroyed faction has a chance to try and make a come-back at some point, you have a situation in which the faction will be continually popping up again and again over the course of the campaign. I'm not sure I like that.