Even though 2019's instalment hasn't been announced yet (though it's pretty obvious that it's going to be Modern Warfare 4), Activision have put the breaks on Call of Duty 2020.
Since Black Ops II, the franchise has worked on a three-year development cycle with three different studios working on releases, Treyarch, Infinity Ward and Sledgehammer. The latter studio was expected to be working on a game for next year, after shipping Call of Duty: WW2 in 2017, which is apparently no longer the case.
After the launch of their last title, Activision apparently put Raven Software - a team which has so far provided support for the franchise - in charge of the 2020 project, with Sledgehammer helping. The move was apparently prompted by Sledgehammer's team being thinned out, as employees left in the wake of the co-founders moving on from the company.
However, the new partnership has allegedly been a disaster, with both teams butting heads and forcing the publisher to step in and can the game entirely, calling in Treyarch to release Black Ops V in its place.
Of course, that cuts their dev time on that sequel from three years to a mere two. In order to speed up development, Sledgehammer and Raven will be providing extensive support, and re-tooling their single-player campaign (which was apparently set during the Cold War) to fit the new sub-franchise.
The shake up is a pretty monumental move from Activision, who had thought to have been enjoying the current three-year, three-studio set up. Not only will this move impact the production of Black Ops V, but it draws every future game into question. There's no way the publisher will miss a yearly release, so that could mean the series shifts back to the two-year cycle it used to be on, which will only lead to even more pressure on the developers themselves, as well as less creativity overall between the sub-franchises.
Activision keep mentioning how well 2019's release is shaping up, but things could be rocky for every studio working on the series after this disaster.