NOT MY WORK! But, found interesting
This is MY prediction as to how the Nav Card will fit into Tranzit
Well, well, well, CoDz. I think I might just blow your minds for a second. You know, have you sleeping with crazy dreams of this coming true. I hope this is the case.
We completed the Easter Egg and never found a use for neither the Nav Card or the Nav Card reader. We have had trolls telling us of Nachtder Untoten answers and nursery rhymes of false answers. I bring you something that is not a claim or an answer.
A Prophecy or Prediction
What is the best, final DLC that you could imagine? Connecting all previous DLCs, right? What is the best way to do so? A domino effect. In Black Ops, the community cried out for WaW maps. Treyarch delivered. Is it not safe to say they planned for it this time around?
We have unexplained coding, and in this coding we can see evidence of not only WaW maps, but Black Ops maps. This may look like a lazy copy and paste job, but it could be something more. Let's say the next map has something else we need to build, but it isn't of use to us like the Nav Card reader. Possibly a Global Positioning Computer. We still have the Nav Card, but the two are incompatible.
This continues until the final DLC, where we obtain the correct Nav Card. Once we go back to the original Tranzit map "Green Run", and insert the correct Nav Card, we will be taken to a new stop with a GPS card for example. This card would take us to another area that has yet another item we need. So on and so forth.
My final theory is that since Nacht might have "buyable" doors on Green Run, this leaves three DLCs for the final three WaW maps. Where do we find the correct Nav Card?
In a Black Ops zombie map pack.
We will receive each of the WaW maps in a Green Run type of map. The final DLC will include all of the Black Ops maps and the correct Nav Card. Once we obtain this, the entire globe will become one big map. Most likely accessible via teleporters.
What do you think? I personally hope I am right.
EDIT: In the Nuketown zombies loading screen, you see a giant weapon of some sort. This weapon is being charged by three beams of energy, and combines this power for a single downward blast. I believe we will activate three towers that will eventually power this weapon for Rictofen/Maxis. Depending on the choice, this weapon could potentially fully destroy the earth, or inject it with mass amounts of 115 for Rictofen.
Note: I have not read every theory regarding the NavCards, or the Nuketown Loading screen, so I am sorry if this has been said before.