Maybe... [THEORY]

[RichieHF]

This is my first theory, and I'm not sure if this has been said before.

What if, Tranzit's NDU isn't just there to bring the map to somehow fit in the story, but it's for us to foreshadow that the next 3-4 DLCs zombies maps will have the original four maps somewhere in them?

[Faust]

Seems possible.

Also, word of advice, title your posts more appropriately so they can get more attention. :)

[CovetousShark6]

I kinda agree, seeing as how there is a leak for Die Riesethat I shall not say anything about but can look it up for yourself and maybe see what I am talking about. I don't really like the idea that much though.