Just curious, could you list tangile points which would lead to a loss for consumers?
The only thing I can think of is MSFT becoming evil and making everything shit and super expensive, in which case talent would leave to create new studios and customers would move to competitors where they would get a better deal.
This is possible because in this industry any game can become a top seller (Vampire Survivors, Stardew Valley, BattleBit for e.g.) and there are competitors like Tencent, Sony, Nintendo, Rockstar, all succeeding without ABK games.
Here are some of the pros I can think of:
Getting access to ABK games under a subscription services gives cheaper access to games as long as the subscription fee is less than $70/quarter, assuming avg gamer buys CoD every year to play for 3 months. And when it becomes more expensive than that, avg gamer would simply buy the games like they currently do.
CoD on GeForce now for next 10 years makes cloud gaming more lucrative, and competitive given how poor xCloud is compared to GeForce Now.
Having CoD on Sony platforms for at least next 10 years leaves enough time for Sony to invest in first party shooters, something they had ignored for so long.
Xbox getting content and quality parity for CoD acts as a equilizer for all gamers, something which Sony was blocking so far with exclusivity contracts.
Microsoft getting some leverage over monopoly of App Store and Play Store to push for lower commisions or alternate stores on respective mobile OSes makes it better for all mobile devs by bringing competition.
AB games coming to steam also sounds like something PC gamers would like.
Microsoft potentially clearing the toxic culture at ABK and allowing unionisation only makes it a much safer and equal working place. It may not lead to high quality best seller games, but I guess ABK can benefit from lack of toxicity at cost of lack of profits.
Update: those who are downvoting, please do share your thoughts. I'm happy to learn more and update my perspective on this.
As someone who's been a Blizzard customer for 30 years roughly. Selling to Activision was a bad move from a customer perspective. Selling all that to Microsoft is utter bobbins. I 100% think Microsoft games division is currently less horrible than Bobby Kotik. It's a real; real low bar. But I know for a fact that as a customer I'd be much more satisfied if Blizzard was independent again and able to develop at their own pace and schedule. And not that of some distant detached greedy CEO focused on quarterly profits, and what they can cancel in the short term to boost them.
Also I have this controversial statement. There should be no locked down consoles or console exclusives for the last 20 years or so. They've all been one of 3 more or less common PC microarchitectures. Intel, PPC, and ARM. Hell before that they were largely Z80 or 6502 based. Those at least ran bare metal with fairly specialized configurations and timings. All the modern stuff largely runs on otherwise largely common commodity hardware with well-known APIs and back ends. Just artificially locked down.
We're not talking about the sale that started Blizzard into this mess though.
There's also a fair few consoles that have come out over the years and are not locked down. Steam Machines are a perfect example - and no one remembers them because they were too expensive. Why were they too expensive? Because they weren't being financed by exclusive products that drove people to the platform to cycle sales.
Even Steam basically made its inroads via exclusivity. When Half-Life 2 came out, it felt like a terrible forced piece of software that Valve was pushing. It's never been technical capability or CPU architecture that encouraged exclusivity - hell, half of Microsoft's good exclusives are made in Unity or Unreal, and some of them ended up getting easy Switch ports.
Actually, everyone is in love with steam machines currently. It took Valve a bit to find the right form factor and application. But they did get there. Have you heard of the steam deck? There have been other hand held PC systems before. But Valve released the definitive gaming one. And the software is there for other hardware manufacturers to use if they like.
And you're having some heavy misremembering of history there. Halflife 2 had Physical releases outside steam. The only console it was never on was Nintendo's. Having releases for PS2/3, OG Xbox and 360. As well as physical releases for Windows and Mac. Correct me if I'm wrong but steam has only ever been avalible for Windows Mac and Linux. So no, Valve didn't play exclusivity games.
If I were forced under duress to pick a gaming corporation as being the good one. Good and corporation are two words that generally don't go together. But Valve would be one of the closest. A generally flat socialist like company heirarchy. Largely platform agnostic. And has done more than any other company to reduce lockin. Their contributions to Wine and Proton are pivotal.