According to a reputable source, "virtually ever studio" at Call of Duty: Warzone) that lead development on each title, there are a bevy of other studios that often get buried in the credits.
Over the years, studios that once led major franchises like Tony Hawk's Pro Skater have been quietly corralled into Call of Duty development. The most recent studio to meet this fate is Spyro Reignited Trilogy's franchises continuation remains unclear, but it entirely possible that it won't be with Toys for Bob.
VGC reporter Modern Warfare sequel or a smaller studio developing assets for maps, weapons, and skins, the franchise has gone almost literally all hands on deck. Toys for Bob, Beenox, High Moon Studios, and more are all assisting on Call of Duty development now, and it raises the question of how much time and resources that takes from those teams and if they have any left over for non-CoD projects.
Activision seems to be metaphorically putting all of its eggs into one basket. That means if rumors of this year's EA lost them, and so much more, but it doesn't seem very feasible for Activision to juggle anything but its single hit franchise at this point.
It's undeniable Destiny in recent years. With the fickle nature of investment, the publisher seems to have built a proverbial house of cards in Call of Duty, and it needs to create a safety net for itself with other franchises should it topple down after a single bad year.
Source: Andy Robinson
