Looking at my brief exposure to Gamepass, over the last 7 months, I've so far witnessed nothing but positive trends. It's the early days honeymoon period still for the service, so things could someday get dark and dystopian.
But the main thing I'm seeing is a lot more support for AA games and indie games, as well as a loosening of the noose around the neck of AAA or AA+ games. When you're not entirely bound by sales numbers, then you have a little more room for risk taking and creative freedom I think. Stuff like the new Aliens game can get played by people now on Gamepass, instead of just instantly buried because it's not a $70 mega budget title.
Sub services have the potential to reawaken game diversity, which has been stagnant for a while now for all the large publishers.