I personally think the story end will end with everyone, after a long series of events leading up to this, will end with time traveling back to the past t stop the zombies from ever being created. I thought the destruction,(or half of) the earth is really just a cliff hanger to this zombies series, like it was a season finale or something.
I'm also getting ahead of myself here with this one, but as i've always thought, because the intense amount of story involved with these new zombie maps, they could just as easily make an entire zombies game, priced like a regular call of duty game, and it would sell like wildfire.