This is about game pass content. I suspect ZeniMax was going to be gobbled up by somebody regardless, and Microsoft didn’t want it to be Activision or EA.
So my guess is the big titles will be cross platform, but Microsoft’s hook is you’ll get them for pennies on an Xbox or PC with game pass.
Sony really wants you to buy a PlayStation, but Microsoft is a software and services company first and foremost. Sony will tout its console sales numbers, and Microsoft will do the same with its subscription numbers. Apples and oranges, really.