So, after looking at some posts and theories, my theory is, once we activate all these towers and insert the NAV card, the last DLC will include all the DLCs from WaW and BO, why you may ask? Because maybe time will be reverted and maybe in Nacht, the marines that crash survive and in Verruct, the Marines there also survive and maybe they save Dempsey from captivity? Maybe in Der Riese, time is set back as far when Richtofen traps Maxis and you are Russian soldiers infiltraiting the plant and instead of Rich trapping everybody, maybe YOU trap everybody so they all die and a new reality forms where none of the zombies form, element 115 is never created and this is where the crazy ride of zombies ends. That, my friends, is an ending I will never forget. Thanks for reading! Post your ideas down beloooooow!