Eventually they will release it for the PS. No one will avoid the huge user base of the PS ecosystem and lose the extra jackpot money that this can generate. Releasing TES VI for the PS ecosystem can provide them with at least half of the PC & Xbox combined revenue. MS is not stupid. This is a PR stunt. And the author of the article knows this.
I wouldn't count on this coming out for the PS4.
So the PS Ecosystem is not going to be massively larger than Xbox when you leave PS4 out. Let alone PC + Xbox.
MS isn't going to be losing out, Xbox and PC covers a vast majority of gamers. Those that are PS only are a minority. And those are the ones MS is trying to sell a product to. Series S is cheap enough for those to get on the Xbox Train for gamepass goodness.
MS has no reason to put their AAA games onto Sony consoles. The Series X is hands down a better console, there is no doubt there. You can boot into dev mode and run emulators. There is game enhancements for older titles, etc. Only thing the PS5 has over the Series X is the better controller features. One area that MS really didn't push the bar.