Of course the player base is dwindling - they emptied the ocean of ships for regular players to engage. And why did they do that? Because the Rube Goldbergesque set of rules governing Port Battles required the ships gone so they are not used to exploit the hostility mechanic.
At some point it might dawn on them that, in light of time zones, Port Battles are the problem. That is the circle that cannot be squared.
Trade and raids, in a vibrant Carib that can be sailed, would be a decent game for most. Alas, the clan-wars mindset forbids that.