https://www.polygon.com/2018/5/17/17365154/call-of-duty-black-ops-4-multiplayer-modes-changes-battle-royale

Treyarch is going back to the future — but not too far — for Call of Duty: Black Ops 4’s competitive multiplayer mode.

The narrative setting for Black Ops 4, which is primarily a multiplayer-focused game and will not include a traditional single-player campaign, is near-future modern combat. Black Ops 4 will be set between the events of Black Ops 2 and Black Ops 3, sometime between 2025 and 2065. There will be some futuristic technology in play, but players wont be fighting as or against robot soldiers.