Well, the answer has finally arrived: maybe.
As far as games we already know about, Xbox boss Phil Spencer told CNBC that Microsoft plans to uphold any previous commitments made by ZeniMax studios regarding console availability.
The commitments we’ve already made with the gamers out there on the games people know about, we will continue with those commitments. The thing this is really about is a huge investment in our Xbox community. They know that the great games coming from ZeniMax and all of those studios—we’re now over 23 studios inside of Xbox—those games will be able to come to the Xbox community, they’ll come to Game Pass day-and-date, and people will just have this amazing collection of great games to continue to play on Xbox.
This means that former timed PlayStation exclusives, specifically Ghostwire: Tokyo, will remain that way. How nice.
Then, in a separate interview with Bloomberg, he said that other future titles would be tackled on a case-by-case basis: so the upcoming Sci-Fi RPG Starfield might come to the PS5, but they're not willing to commit to the idea.
I can't see a world where Microsoft would be overeager to share Bethesda's bigger titles with the folks over at Sony, especially since they've got 7.5 billion bucks to pay off. Still, it's not impossible that Sony could twist their arm on the issue... at least, for multiplayer games where a bigger player base is better for everyone.