While we already know that this years Call of Duty Call of Duty: Modern Warfare will be a soft reboot of sorts for the Modern Warfare saga, it seems theres a spillover marketing/advertising of some kind thats happening now between this years COD, and last years COD game, Black Ops 4.
Source: N4G PC Call of Duty: Black Ops 4 Captain Price Skin Being Offered as a Modern Warfare Pre-Order Bonus