It would be cool if there were for example 4 different pirate factions that a player could choose from. Every faction would have their own outpost located in the outer corners of the world map. At a faction outpost you could then buy special faction voyages which earns you coins and reputation in the faction. You can only do these voyage with faction members in your crew.
Some factions could have a certain pirate code, like being friendly or hostile.
And when ship customisation becomes a thing they could add some sort of faction logo and flag to a ship. So you can identify someone from another faction and you know when to attack them. Ofcourse you are not allowed to attack ships and players from your own faction.
