I wouldn't bet on it, but I think that while MS will try to make as many Bethesda franchises as possible PC and XS exclusive, TES and Fallout will remain multiplat, their sales potential on PS is too high to give up. PC and XS timed exclusive for them is very likely, though. Also because existing deals with Sony must be respected, so the first exclusive titles would arrive too late to help XS significantly against PS5.

True, but at the same time Microsoft knows that it wouldn't be moving consoles or especially Game Pass subscriptions en masse if the major franchises were multiplatform. It would be the equivalent of Sony releasing God of War, Uncharted, or The Last of Us to Xbox as well, knowing they're leaving millions of copies unsold by not releasing those games on Xbox. Microsoft is really pushing Game Pass extremely hard, and I can't think of a better way to do that than making those franchises day 1 available on Game Pass exclusively. Or maybe a year exclusively, then a $70 price tag on those games for PS5.

Yes. Respecting existing non-exclusive deals with others leaves MS many possibilities to favour its platforms anyway, also because when Sony and Bethesda stroke their latest deals Game Pass either didn't exist yet or it still had little relevance, not to mention that before Game Pass Sony most probably still considered PC gaming mainly as MS internal cannibalization against XB. On future games not included in any existing deal MS hands are totally free, and a long timed exclusive can give it every advantage, including higher profits. Nadella's gentle strategies are way finer than Ballmer's brute force, Nadella even allowed Game Pass on Android: after Ballmer lost the mobile train letting Apple and Android win quite easily (he was so busy fighting a possible, bur actually inexistent PS competition against Windows that he didn't see the true dangers coming), even Windows could be at risk in the future, a HW- and OS-agnostic gaming platform can  even be a starting point for a future general purpose MS platform.

So it's official : https://www.nintendolife.com/news/2021/03/bethesdas_future_games_will_be_where_game_pass_exists

Future Bethesda games will be released "where Game Pass exists".

Phil Spencer's quote:

"So obviously, I can't sit here and say every Bethesda game is exclusive, because we know that's not true, there's contractual obligations that we're gonna see through as we always do in every one of these instances. We have games that exist on other platforms, and we're gonna go support those games on the platforms they're on. There's communities of players, we love those communities, and we'll continue to invest in them. And even in the future, there might be things that have their contractual things or legacy on different platforms that we'll go do."

"But, if you're an Xbox customer, the thing I want you to know is this is about delivering great exclusive games for you, that ship on platforms where Game Pass exists. And that's our goal, that's why we're doing this, that's the root of this partnership that we're building, and the creative capability we will be able to bring to market for Xbox customers is gonna be the best it's ever been for Xbox after we're done here."

I'm glad we got this clarification from Phil. Now we don't have to keep hear the speculation about what games are going to be where. 

Let the GamePass on Playstation speculation begin.