Faction Home Regions - if taken, the whole faction dies?

[magnum]

I have seen Pirates return after having eliminated them. I don't recall specific circumstances under which it occured. They did re-emerge in the Americas though.

[Monsieur Alphonse]

I have seen Pirates return after having eliminated them. I don't recall specific circumstances under which it occured. They did re-emerge in the Americas though.

Yep. If you kill the French or the UP their islands will become a new pirate stronghold and the pirates will reemerge.