DrewC writes to us in the latest POTBS Dev Blog on the specifics of upcoming changes to PvP in Pirates of the Burning Sea. The latest patch introduces duel and skirmish modes and will also address balance issues relating to port defense gameplay.
That said, there have been two major things making port defense by unrest removal completely nonviable. First the aforementioned economic turn in missions. I'm sure you're all familiar with the issue there, and we've got the short term fix in place. In the longer term we want to make the economic turn in missions a slow burn of unrest, rather than a bomb. This is not a change we're going to be able to make immediately, it requires some serious work to make happen, but it will happen. The system to do so is also somewhat complicated, and really deserving of its own devlog.
You can read the full story here.