Will's job was done. He was returning to Elizabeth and his son. Another poster pointed me in the right direction.....
From Wikipedia:
After the credits, in a scene captioned "Ten Years Later," a young boy approximately ten years of age is seen singing "A Pirates Life for Me" as Elizabeth walks behind him. It is implied that this is the child of Will and Elizabeth. The sun sets followed by a green flash and Will, on the mast of The Dutchman, sails towards the shore. According to the film's writers, the curse of The Dutchman is broken if, after the ten years, the captain's lover reamains faithful. The final post-credit scene suggests that Will can now return to land, as Elizabeth has remained faithful. The green flash, which symbolises a soul returning from the dead, supports this theory. Apparently, a scene of dialogue between Tia Dalma/Calypso and Davy Jones, which explained this, was cut from the film, leading to confusion about the ending.