Don’t expect the Call of Duty titles (or any of Activision‘s games) on GamePass right away. According to Phil Spencer: People think the deal’s gonna close and everything’s available on Game Pass. That’s not true.People think the deal’s gonna close and everything’s available on Game Pass. That’s not true. (GameSpot)
He adds that this delay isn’t specific to the Activision-Blizzard acquisition, noting that Microsoft’s previous acquisitions have always required time to get native games up on Game Pass. Looking back to Microsoft’s acquisition of Bethesda in 2021, it definitely didn’t take long before Bethesda games started appearing on Game Pass, with 20 titles from the studio’s back catalogue added just three days after the deal was finalized.GameSpot
I wouldn’t expect it to be immediate, but I do expect Activision games that are already in a backwards compatible situation to start appearing immediately on Xbox GamePass.