Call of Duty: Black Ops 3 has been incredibly successful and with the current negative response to Call of Duty: Infinite Warfare, it would make sense for Activision to push for the development of the next Black Ops game.
Treyarch Studios are the developers of the Black Ops series and have previously commented on Twitter that they were looking into developing Call of Duty: Black Ops 4. The games in the series have so far been released with 2 or 3 years in-between them and so far the gap has increased by a year with each release.
This isn’t very good for predicting when Call of Duty: Black Ops 4 will be released and rumours are also limited right now.
If Call of Duty: Black Ops 4 is in development right now then Treyarch Studios is being extremely careful with the details for this game. Black Ops 4 will most likely be revealed sometime next year and released in 2018.
Infinite Warfare is the next confirmed upcoming game in the Call of Duty series and currently fans are hoping for a dedicated zombie edition; one that contains every zombie mode and map ever created for the Call of Duty franchise.