Most end game content is farming. There's also a plethora of side quests and companion promotions you can do, which keep most people busy for 2-3 months. Tower of Moo Manchu and Kane are where most farming goes on atm, but once skeleton key bosses hit live, I could see those becoming quite the attraction.

If you get (or find a friend that has) a Smuggler's Arena, you can also battle the enemies in there. You could also work on decorating a house with furniture from the bazaar or fight drops. You could also try a different pirate class and see how it is different. Some of the crew quests would be new to you. We all are hoping for another world to be added.

The staff at KI have mentioned that they are thinking about how to add a fishing side activity to the game. There are other side activities that the parent game, Wizard101, has, which may at some point be added to Pirate.
So far, they added, since the game began, Pvp, Ship Pvp, Pet games, pet Pvp, the Nautical Regatta- battling enemy ships, a housing gauntlet for purchase, the team up ledger, and the key bosses were just added to the test realm. At least it is a hopeful sign that new things are still being added to the game.