With the first expansion introducing the French army on they way, the Battlefield 1 Premium Pass page has been updated to include the names and locations of the three other expansions. Thus, They Shall Not Pass will be followed by In The Name Of The Tzar, which will focus on the Russian army and snowy environments. Third in line, we have Turning Tides, which will take players through the Gallipoli Offensive. For the fourth DLC, only the name, Apocalypse, and a vague (well, vaguer) description was given, leaving us guessing.
Right now, the Premium Pass comes with the Deluxe Edition items as well, so, if you haven't gotten your hands on it yet, you might consider doing so.