The 4 world bosses that you need to kill to get the legendary cloak are the Sha/Na'lak equivalents for 5.4, and drop PvP gear (as well as tier gloves/legs). Now that I think of it, will they even be available for the first week, because the PvP season doesn't start for a week? In past tiers, they have not made PvP gear dropping bosses like that available until the PvP season started.