I watched recently Pirates of the Caribbean: Salazar's Revenge and one thing I do not understand is why one of the plot devices in this film is the idea that William Turner is cursed. Sure, it looks like a curse, but it was established in the earlier films that someone has to ferry the souls of those who died in the sea to the afterlife. If nobody does that, what would happen? Do you think this is a plot hole?
The reason Will's position as Captain of the Flying Dutchman can be considered a curse because of the contextual material. Will wants nothing more than to be home, with his family. However, he is bound and incapable of leaving his post. He physically cannot be freed nor step on land unless he is either A) forced into premature 'retirement' (his heart is stabbed) or B) his curse is broken, and all bound before the mast of the Dutchman are freed.
As for who would ferry the souls, I am pretty sure nature (or Tia Dalma/Calypso) would find a way to free the souls lost at sea. Nature typically finds a way.
Food for thought- What if souls who died at sea remained at sea because of a curse? this would undo the entire mechanic of/need for the Flying Dutchman and her captain.
Potential plot information below
Perhaps it is the reason Davy Jones comes back at the end of the credits
If nobody does ferry the souls of those lost at sea, I am sure nothing will really happen other than the souls collecting in the ocean. Much like sand. Its a bit sad to think about (from the if-fantasy-were-reality point of view) but it IS just a movie. so not really a huge deal.