If Sony keeps refusing Gamepass on PlayStation, that will only provoke MS into buying more studios. The sooner Sony swallows their pride and accepts Gamepass (with a cut of the subscription for themselves, of course), the sooner Microsoft probably stops buying major studios and focus on more organic growth.
Some of the acquisitions Microsoft has made have been about increasing their first party offerings alone. But I'm convinced a huge part, if not the majority reason they bought Zenimax and Activision/Blizzard was to force Sony to submit to Gamepass.
If Sony continues to be stubborn then I suspect Take-Two, EA, and maybe even Ubisoft will be swallowed up soon by Microsoft (in the next 2 years). Then Sony will be begging MS to let Gamepass on PS devices out of fear that their hardware sales will plummet (which would then cause their first party sales to plummet).