Just had a thought. Phil Spencer mentioned that MS envisions gaming being cloud-first and scaling up and down devices and not be bound to capabilities of the local hardware. I think the reason why MS can do this without the operating cost skyrocketing based on data used by gamers is because they own the infrastructure.
I think Microsoft owning the data centres they are operating will be a MASSIVE advantage in sustaining a cloud gaming subscription service like Game Pass at scale. You see, the pricing model for Azure is the more MB used, the more you pay. Microsoft doesn’t have to pay for renting out server capacity (they own the data centres), so this means that they can have games that use unlimited CPU, GPU power or have over 100,000 players in a single map they envision coming. Whereas Sony or anyone not owning their infrastructure could potentially run in a situation where subscribers will use more data than the subscription pricing can sustain or more than actual subscribers, or the more complex the game, the more expensive it will be for company in operating the service/game. That alone is why Sony for example will be resistant to expanding PSNow.