There was at least one thing that you kinda forgot about. Sure Will made a vow to save his dad, but he also lost in the game to Davy Jones which means, technically, he's part of the crew for all eternity already.

Not exactly. Have you played that game before? It's one of my friends' favorites. The person who made the last bet is the one who ultimately wins or looses. So no, Will didn't loose or win. Davy won and Will's dad lost.