So I saw a post that suggests that the Call of Duty: Ghosts timeline continues the events of Modern Warfare 3.
During the mission "Federation Day" in Call of Duty: Ghosts, there is a TV that is broadcasting in another language, supposedly the reporter says in another language "Our foe is crippling as suggested from 2016. It won't be long until victory" I believe they are referring to the Russian Invasion of the United States in Modern Warfare 2 and 3.
Also in the mission where you are fighting on the "Atlas Platform" in Call of Duty: Ghosts, one of the enemy says supposedly in Spanish "So, are we going to Europe?" and another one of the enemy's responds "The Russians already did enough damage to Europe, and that is the key to our victory" I believe they are referring to the Russian offensive in Europe during Modern Warfare 3.
If any can confirm this for me, it will be much appreciated.