I feel we knew this already; announced platforms will be respected and inked deals remain unchanged. We've seen this already with two PS timed exclusives remaining timed exclusives even though Microsoft now own the studio.
The question is... games like Starfield and TES6 never announced their platforms: are they exclusives? The answer, I feel, is of course they are - Microsoft paid for them to be exclusives.
I think it's more nuanced than that.
1. Deathloop / Ghostwire Tokyo aren't good examples. Sony bought their exclusivity by paying money / doing a contract. If MS stopped that exclusivity, they'd be breaching a contract and paying Sony the damages + returning the contract money + the PR shit they'll have to face. It wasn't a viable option to do so. MS made the right call.
2. TE6, I agree. That's a long shot because the game is likely years away.
3. Starfield? I think it'll be multiplatform. MS didn't pay for that exclusivity (not until related information pops up about a new MS contract). Besides, MS didn't pay the development cost of that game, and a PS version was being developed from the beginning. So there are two options for MS:
1) Scrap the PS version, and recompensate the developers (this will be in addition to the $7.5B acquisition), or
2) Let the game release on both platforms as was intended before the acquisition (which is what MS will do, if we are to believe this quote).