I don't think Will's coat looks that much like Davy Jones'...DJ's coat seems like it has some gold on it, much like a captain or even a naval officer would wear. Although....now that I think about it, it could actually look similar to Will's coat in the wedding.
Not saying that it isn't possible for Will to stab the heart and all that, of course.
However, I can't help but wonder if the writers haven't tossed in a bunch of clues to point us in one direction, but then they won't just suddenly do something so unexpected that we won't all go "OMG, I never even saw that coming!"
I would totally dig that. In fact, I hope we're all completely wrong about everything and AWE just completely blows us all away. I love twisty plots. 😄