With that recent Bethesda video about single player games at the Game Awards, I wonder if that might have played into them doing more game work on Nintendo?
After all, what is Zelda and Mario but a single player game, and they dominate on the Switch where the other consoles are dominated by multi player games?
I don't think it has anything to do with Nintendo. It's probably just a reference to either Microsoft or EA saying that "single player games are not as popular any more".
If Bethesda make an Elder Scrolls 6, it will naturally release on PS4, XBO and PC at the very least.
And "dominated by" doesn't matter as long as single player games still do well. And we have many great examples of that on PS4 in recent times.