Little threat - MSFT won't stop selling the games from Bethesda on playstation. Only thing i can see if MSFT saying the games are available but ONLY through gamepass....so in other words trying to use games to force gamepass not the playstation. Unlikely though as you could see Sony retaliating by ending cross play which keeps the servers going for MSFT with their smaller user base. In the end MSFT will offer games on gamepass and sell them full price on Playstation.
Of course they will. Why would they buy Bethesda if in the end they just wanted a Game Pass deal? That's delusion.
I wouldn't say Game Pass is a threat to Sony per se, but the Game Pass model will be the default way people will consume games in the future. Most consumers buy a game, finish it (or not) and just move on forever, they don't care about having game cases around. It's how we consume music, movies and books nowadays, we check Netflix, watch half a movie and move on. So in that sense, models like Game Pass are inevitable and Sony knows it. The only thing we don't know yet is how it's going to be sustainable to publishers, but they already have other means to monetize, like MTX and those are going to be mandatory to big projects.
So if we think as collectors, yes, we care about owning games, but most people don't collect, they just consume. The old business model is faded to die.