Now, as we know, Der Eisendrachen has been confirmed to be DLC 1 for Call of Duty: Black Ops III. This map is set in the Hohenwerfen Castle in Austria. The castle itself, however, has a dark history that I think may be exploited slightly in the map itself.
The castle was built somewhere between 1705 and '08 of the same year. The original owner at this time was one Archbishop Gebhard of Salzberg. As time went on, the Wikipedia page I pulled this information on states that it eventually became a POW prison for the Austrians. However, this is not all that I wish to touch on.
According to my father, a huge history buff (he actually was studying to become a history teacher at one point), the Wikipedia article is actually off. He states that it was in Romania, which is not the part I am majorly concerned about. The part that majorly concerns me about his lesson is the owner of the castle: Vlad the Impaler. I do not wish to go into all the gorey details, but, to put it simply, he makes the poor Allied soldiers ran through on Origins look like a joke. Personally, I think this story may have something to do with the easter egg, but that is for another day. Vlad was also the origin of the Count Dracula mythos (if I can call it that) due to one of his killing methods: feeding people to vampire bats. Beyond this, he is also said to have a glass of his enemies' blood at the table with him, and, although there is no historical proof, it was believed that he drank it at the time.
Considering that the current setup of late BO2 (Origins) and our current BO3 maps (Shadows of Evil in particular) seem to each have a level of this within them, with Origins having the aforementioned impaled Allied soldiers and the Crazy Place (a bit of a stretch here, but I think Vlad may have been crazy.) and Shadows of Evil having rather bloody rituals and an involvement in another mythos (hence why I used the name above) there is some room for acknowledgement that this may not be terribly far-fetched to say that Vlad's actions may have not only influenced Der Eisendrachen, but Origins and SoE before it.
Beyond this, I want to make another, very subtle connection between Origins and Der Eisendrachen: their console codenames. Origins is zm_tomb, and Der Eisendrachen, if the wikia page is to be trusted, is zm_castle. Now, we already know that Dracula lives in a castle, and sleeps in a coffin in accordance to the mythos, but what could that possibly do with a tomb? The simple answer is this: everything. A tomb is one of the places where bodies go to rest, the other being a graveyard, in a coffin. Given that the tomb has already been covered in Origins, and the graveyard, in a way, in Shadows of Evil (we basically have eight known humans dead in this map, the four playables post-EE and the four rituals), who's to say that the coffin, more specifically, it's inclinations towards Dracula, and therein, Vlad the Impaler, could not be covered in this map? Even if the location says we're off, the Dracula mythos states he lives in Transylvania, so, we may not see Vlad himself, but I do think that we'll be seeing some heavy influence.
Note that this is all speculatory, I do not even have the game yet (if you do not believe me, check my Steam, it's on the Profile page), and the catalyst of the speculation may be from an unreliable source in the long run, but given all the comparison I layed out above, I don't think that it is a major stretch.