Even though Call of Duty: Vanguard got mixed reviews and did not sell as well as we've become used to from the series, it seems like Activision Blizzard still has confidence in the developer Sledgehammer Games. According to the Exputer journalist and insider Tom Henderson, the studio is already in pre-production of their next game in the series.
It should be noted that Vanguard had a lot of problems during the development and was delayed by a year, which only gave Treyarch two years to deliver Call of Duty: Black Ops Cold War, as this was used to fill the gap. This year, we're getting a new Modern Warfare from Infinity Ward, but 2023 won't have a proper new Call of Duty title, which will be the first time this happens in almost 20 years.
Instead, the developers will use this extra time to polish and upgrade the Call of Duty experience. As Microsoft is expected to take over Activision Blizzard next year, the plans for the series might change going forward.