Those discussing someone taking a chunk of COD, while I don't doubt that it is desirable (Blundell having his own Sony studio surely has this aim), one of the key elements that makes COD unassailable is their release cadence.
Even if a studio were to make a genuine competitor, would they be able to go again the next year? The year after that. Almost the entirety of Activision is focused on that cadence.
The only way that it can happen long term would be to have a GAAS game that evolves over multiple years to take on Warzone.