Surprisingly, them keeping your (and the author's, and other abandoners') files probably makes more business sense than deleting them: the files probably don't cost that much to store (my hunch is most abandoners don't have TB's of data), and since they all still have an account, DropBox can spam them with these threats and maybe some percentage of them do return, allowing DB to make money off them.
If the files get deleted, both sides know it'll be the end of their user-provider relationship.
If the files get deleted, both sides know it'll be the end of their user-provider relationship.