Is zero sum a problem?

I like that bch has solved the scalability problem in regards to block size, but if we are going to have "perfect" money, don't we also need to scale supply some how proportionally with number of users? Not suggesting how at this point, it may be complicated. But isn't it obvious there is a need? In galactic year 3000 when we have 10T+ humans in our galactic arm of the milky way, we are saying that the protocol only allows 2.1 billion things to exist, it's clearly not designed to scale with users and what theoretically do we do at that point? I think there should be an algorithm that modifies the supply in these edge cases to scale properly. Feels like we're close to theoretically perfect money if we figure these edge cases out so it lasts really forever.