https://www.pcgamer.com/change-is-always-going-to-be-hard-for-people-says-call-of-duty-black-ops-4-studio-head/

The Call of Duty: Black Ops 4 reveal event confirmed, as rumored, that the game will not have a "conventional campaign", but will instead feature a large-scale battle royale mode, Blackout, complete with land, sea, and air vehicles from the previous games. 

In an interview with Eurogamer, Treyarch's co-studio head Dan Bunting responded to fan feedback, and confirmed that a "traditional campaign" had never been planned for the latest Black Ops title. He also detailed what activities were going to be available to players who still want to play alone.