The problem with game pass is that it takes the Spotify model to games. In practice, it doesn't seem to scale well - Microsoft has seemingly hit a market cap of ~35 million users because of a lot of existing aversion to subscription services in games, which isn't enough customers to actually amortize the cost of development, even at an indie scale.

Indie developers in particular don't like Game Pass because it apparently pays Spotify-tier rates, which is pretty bad. Spotify gets away with it because it took a deal with all big music labels for more favorable payouts, but your average indie band on Spotify makes absolutely zilch from your Spotify subscription, even if you listen to them 24/7 every year. Indie bands typically compensate with concerts and brand merchandise, but that isn't an option for games - secondary income sources are typically reviled (microtransactions in paid games) or don't sell to expectations (merchandise). The Spotify model only "works" because they shifted the music industry to rely primarily on those "side" sources (and even then there's a lot of disgruntled musicians who are unhappy with the Spotify model devaluing their craft).

It's true that Game Pass subscriber growth has slowed, but I don't think 35 million is any kind of permanent cap. There are 910 million PC gamers in the world today, and this is growing by approximately 35 million per year. This is, of course, in addition to Xbox owners. As more people become PC gamers each year, more people discover and subscribe to Game Pass. Ditto for existing gamers who discover Game Pass, or decide to finally try it and stick. Tastes and expectations are changing, and just as we accepted subscriptions for music, I think subscriptions for gaming are becoming more normal.