According to sources for Kotaku, Treyarch and Activision are working on Call of Duty: Black Ops IV.
These rumors originate for a tweet by Marcus Sellars saying that Call of Duty 2018 will be Black Ops IV and will release on Xbox One, PC, Playstation 4, and Nintendo Switch. Sellars also said that the game will be”set in modern times and is boots on the ground.”
COD 2018 is Black Ops 4 and is coming to PS4/Xbox/PC/Switch. It is set in the modern times and is boots on the ground. The Switch version will support DLC, HD Rumble and motion controls. The Switch version is also being ported by a company which is familar with COD games.
— Marcus Sellars (@Marcus_Sellars) February 4, 2018
Please keep in mind that Treyarch nor Activision have made an official announcement. The Kotaku article also uses anonymous sources, therefore we are classifying this as a rumor.