Part of the problem is that since Sony is so heavily invested in exclusives, if Microsoft doesn’t have any exclusives and all their games also come out of Playstation, that’s incentive for people to purchase a PS5 over an Xbox because they know they’ll get all of the games that both Sony and Microsoft make. So even if Microsoft doesn’t want to do exclusives, they kind of have to if they want to keep people from just purchasing their competitor’s console.
I’d be pretty surprised if MS is allowed to purchase another huge publisher. Zenimax was pretty small, but ABK is huge. But who knows at this point…