We have already seen 3rd party AAA games launch on gamepass.The “AAA” games that will release on gamepass are going to be from Microsoft. No 3rd party publisher is going to agree to put single player games on a service day one.
We will see what effect putting big single player games on the service will be for microsoft very soon
Established franchises probably won’t. But new/unproven games and concepts can and do benefit from launching on gamepass.