Warning: Spoilers for At World's End and Dead Men Tell No Tales.
Davy Jones put a curse on his heart, making sure that anyone who destroys the heart must remove their own heart, and preferably keep in in a box. Now, with the destruction of the Trident in Dead Men Tell No Tales, all the curses are lifted, and Will Turner sails up to the shore on the Dutchman, where an elated Elizabeth (the keeper of Will's heart) meets him and they make out. Seems good.
Except she's got his heart in a box - a heart that, judging by the big scar on Will's chest, was removed by relatively non-magical means. And un-cursed people tend to be in trouble when they are on a ship and their heart is in a box on land. So, what's the deal with Will's curse? Did his physically removed heart find a more magical way of making its way back in? Was the heart brought to him really fast by someone right after the Trident was destroyed? Does un-cursing accommodate to living with your heart outside your body? Is this ever addressed by the makers of the movies?