I would agree on Jinbe is the new nakama theory if he weren't 46 years old.
But Jinbe might want to join the crew intentionally to protect Luffy. He might want to stick with him.
And about the Chapter 620. Are we going to get it 3D later? Or…
Brook is almost twice Jinbe's age so age is not stopping him however i would like someone else because most people cannot spell Jinbe correctly and it's funny because of the people who do it are the people that point out spelling mistakes lol.