LittleBusters
Banned
If the number of gamepass subscribers were to stay at 15 million (that number is obviously increasing as we speak, I'm just being modest here), they make up the 7.5 billion in just 4 years. Realistically, about 3 years.
By then (2023), almost every 1st party exclusive game announced thus far (and unannounced ones from Coalition, Id, MachineGames, Compulsion, InXile, Arkane, Tango, Double Fine, etc) will be available on Gamepass, making it an undeniably attractive value for consumers (and will probably have around 30 million subscribers by then).
And that's when giants like Fallout and Elder Scrolls (as well as the next wave of games from every other studio) come out to play for the second half of this gen.
Microsoft's pockets are not to be watched, this generation.
They're spending big money because it makes sense to.
I think realistically Game Pass can go up to 30 million subscribers by 2025.