We live in an exponential monetary system so the money supply has to be exponential in nature and character to fit in with it. If bitcoin were to ever challenge let alone replace our existing money supply it would to change to an exponential currency.
Yes that's right bitcoins would have to become exponential. to be used in an exponential system (this is why we use credit, credit has the ability to be exponential). they would have to be able to grow with he system other wise you have two opposites. An exponential system of using resources as in today against a finite resource bitcoin or gold used as money.
Now this statement is different to reality as bitcoin as it is today is not exponential as there are only 21 million of them.
For any monetary system to work it has to have the ability to grow or shrink with the population and the resources being used by those people. it can not be finite. It has to match goods and services being used and keep value with those goods and services. If you were to change the rules on bit coins and allow it to grow and shrink as needed then yes it would work but, not in it's present form. Not unless you change the real world to fit the way bit coins work.
The question was imagine bitcoins became a major world currency.You still don't know what you're talking about. The quantity of currency does not have to change with the quantity of available goods and services. The currency merely then allows you to purchase more goods and services.
Never mind that there are 21 million Bitcoins are divisible to eight decimal places, which means there are 21 quadrillion base Bitcoin units (Satoshis). If that is not enough, there could be localized Bitcoin block chains, or a separate block chain for larger or smaller amounts.
I reiterate,
you don't know what you're talking about.