As it seems, there was a pretty hefty update awaiting us on December 2, but now it's being announced via Twitter and elsewhere that plans have changed.
"Update: Season 1 of #Vanguard and Warzone Pacific will now release Dec. 8. Vanguard owners will have 24-hour exclusive first play access to the Caldera map. Open access begins on Dec. 9."
In short, Dec. 8 is the date for the update, which adds more Zombies content, as well as multiplayer levels for Vanguard, as also includes Warzone's Pacific stage, among other things. If you don't own Vanguard, however, you'll have to wait until Dec. 9 for the latter.