Microsoft announced that they agreed to acquire Activision Blizzard King. This information was posted on Microsoft’s Xbox Wire website, with a banner showing significant characters from several of Blizzard’s games, one Call of Duty character, and an image from Candy Crush.
That doesn’t necessarily mean that all of those games will come to Xbox. For example, Diablo II: Resurrected launched on Xbox One and Xbox Series X|S. (In addition to PS5 | PS4, Nintendo Switch, and BattleNet.) I’ve been playing it on Xbox S. Diablo III is available on Xbox One, and Xbox Series X|S, BattleNet or Nintendo Switch. Those games are currently on Xbox.
Diablo Immortal is an app game that is currently still in testing. When it launches, players can obtain it through the App Store or Google Play. As far as I can tell, Diablo Immortal is intended to be played on a phone or tablet, so I don’t see it coming to Xbox.
Candy Crush also makes app games that are on the App Store or Google Play. The King website notified players that Candy Crush Saga will no longer be available on the website as of March 31, 2022. I suspect this means King wants to focus on apps. Hearthstone is available on Mac and PC and also on phones and tablets as an app. But, that doesn’t mean there will be a playable version on Xbox.
Overwatch can be played on a PC (but not on a Mac). It also is possible to play it on Xbox. Overwatch 2 has been mentioned, but appears to be on hold for now.
What about World of Warcraft? The official WoW website tells me that WoW is available on Mac (which is what I play on) or PC. There’s no mention of consoles at all. If you do a search for “World of Warcraft on Xbox” you will see a bunch of articles that are speculating about the possibility of it coming to Xbox. But, that does not confirm that this will happen.
Activision’s Call of Duty games are on Xbox – but not necessarily on every type of Xbox console. Call of Duty: Black Ops Cold War is on Xbox X|S, and Xbox One. Call of Duty: Vanguard is on Xbox One, Xbox X|S. Other Call of Duty games are not on Xbox.
There has been some concern that Microsoft will decide to pull all Call of Duty games from Playstation to Xbox. CEO of Xbox Phil Spencer has quashed that rumor in a tweet in which he stated that he spoke with leaders at Sony, and expressed desire to keep Call of Duty on PlayStation.
In short, some of Blizzard’s games are already on Xbox. Some of Activision’s games are. We will have to wait and see if older “backwards compatible” games from these companies end up on Xbox consoles.