We can speculate the roadmap of xbox game studios games and playstation game studios. Doing this will give us an idea if zenimax game exclusivity would be necessary for xbox or not.
So from sony we have returnal, rachet and clank, horizon forbidden west, and possibly god of war and GT7.
For xbox we may have something from compulsion games and halo infinite.
Sony - possibly something from bend studios, Japan studio project siren - gravity rush 3? Pixelopus - concrete genie 2? New iP, japan studio asobo team - astro bot 2, VR game?
Xbox - fable, forza, everwild, Wolfenstein 3,
Sony - japan studio - who knows? , London studios VR game. This seems a very quiet year for sony first party.
Xbox -Avowed, starfield,doom 3, hellblade 2,
Sony - ND -TLOU3 or new ip, insomniac -spiderman 2,
Xbox - gears 6, dishonered 3, wasteland 4, psychonauts 3, the evil within 3.
Sony - horizon 3, god of war 4? And a couple of japan studio games.
Xbox - halo 7, wolf 4, a rare game, elder scrolls 6, forza
Of course there will be differences and 3rd party deals, but the point is the acquisition of zenimax does not overcrowd the xbox line up, it now makes it competitive, better imo.