Here is one of my theories on the girl in the poster. The group obviously has the ability to transfer souls (atleast Richtofen and Samantha) so we know that they will/would be able to transfer her soul into a better suited host. The zombie head that the girl is holding could be Rictofens after she transfers out of it.
This poster shows Samantha. After the group blows up the earth on moon they all enter a cryogenic chamber in a safe part of area 51. 50 something years later, in the future, they awake and transfer Samantha into Sgt. Anderson. They then team up with 4 other mysterious characters and fight zombies in the now futuristic war zone.
Sgt. Anderson is a character in the campaign that works along side David Mason. Her first name is Charlene. Charlene Anderson is taken in the middle of the actual campaign which suggest that Dempsey, Nikolai, Takeo, and Samantha kidnap her to make the transfer.
This is all speculation of course.
