I think the next world for Pirate101 should be Grizzleheim. I have a couple reasons why I say this:

1. They have a tent and representative in Circus Maximus.

2. When making a new pirate, you can select Grizzleheim as an option for where your pirate was raised.

3. I know of two boss creatures who use raven character models. (i.e. Skreech, who is part of Old Scratch's first promotion quest.)

4. Grizzleheim is a world based on courage, honor, and glory through battle.

5. Think of all the companions/creatures possibilities.

If you see any flaws in my reasoning, feel free to call me out on it. Also, feel free to reply with your opinions on what the next world should be.