If Bitcoin is successful, that will have to happen eventually. There's only 300,000 sats per person in the world (less than that if we assume some BTC have been lost). People have already tried to address that perceived insufficiency through things like millisats. When we fix it at the consensus layer, which will practically require a hard fork, it would be nice to address the problem forever by allowing arbitrary precision, e.g. allowing output amounts to be defined as a fraction of MAX_MONEY. If that happens, the idea of base units goes away If you assume that we'll never add inflation to Bitcoin, then the monetary constant is the supply, not the fraction of it that we currently transact in.