If Satoshi becomes so expensive that it cannot be exchanged for anything, it may create some problems for using bitcoin in everyday transactions. However, in this case, there are several possible solutions:
1. Dividing Bitcoin into smaller units: If Satoshi becomes too expensive, it is possible to divide bitcoin into smaller units to facilitate transactions with smaller amounts. For example, you can create a new unit equivalent to 1/100 Satoshi to be able to conduct transactions with smaller amounts.
My only confusion is as to how one could continue to subdivide bitcoin without effectively "creating" more bitcoins, thus bypassing the 21 million unit hardcap. Its not that I don't believe you, I suppose I have the wrong understanding of what it means to make a smaller and smaller unit. Would that not merely be increasing supply, which is not supposed to be allowed? Or is it something that merely exists on a spreadsheet and doesn't really impact the value or supply or bitcoin overall?