Here is what this game desperately needs:
The ability to que for fights while in port.
Why?
The game itself is amazing, but holy crap does it take forever to get the ball rolling on pretty much anything. Eventually players realize they will get more fun/excitement from other games for their time and leave. That's what I did. Loved the game. Hated the time it took to actually play it (waiting for npcs. Sailing across the world with the hopes of finding some good action, etc). When you only have an hour to play and that whole hour is spent sailing in search of something to do, you soon realize that you'd be better served playing something else.
So you should be able to enter a que to join various types of fights (Frigates, small vessels, light lineships, heavy lineships, etc). You should be able to use your own ship (the one you're currently in, assuming it meets the criteria for the fight).
Casual que: You don't lose your ship if it sinks. This is to counterract the increased number of fights happening total, so the que wouldn't be a huge drain on resources. also provides a good environment to learn the game and have fun! Maybe tie in daily quests for doing a certain que, etc. for a nice little gold reward.
Competitive: You lose your ship if it sinks. But if you win you rise in rank on an online leaderboard. You also get tiered competitive que rewards (I like the idea of colored sails: eg. Blue sails=Tier 3, Red=tier 2, black= tier 1).
Now where does RvR and open world still stand with the addition of a que? Its still there! Econ would still require open world sailing and dealing with privateers and pirates. If you were still inclined to spend hours in the open world hunting, you would still be rewarded with the chance of taking someone's nice stuff, etc. Ports would still be necessary for econ, and RvR would be the way to get them.
Over the years I always wondered why more pirate/sailing games weren't made, but now I realize it is because it takes way too long to do almost anything. People play games to have fun, and once you have done the open world thing hundreds of times, the only thing you begin to notice is just how long it takes to get to the thing you actually want to do: get in a fun fight, etc.
The actual battles in this game are amazing and that is this game's salvation: make the fighting as easily accessible as possible. Turn sitting in port doing nothing to actually having fun and playing the game.
Edit:
I would also add that que'd fights can also be a platform for new, exciting game modes: Imagine a VIP mode where the teams objective is to sink the enemies vip and protect their own.
Or how about a treasure fleet mode where two teams are not only fighting each other, but also fighting an npc treasure fleet and competing for how many ships they can sink. Team with most npc kills at end of round wins.
How about a death race mode where you bring your fastest ship, and the objective is to get to the next capture point while fending off the other ships from getting there first?