But this is just a question of granularity. When Zimbabwe hit hyperinflation they printed trillion-dollar notes because the 1-dollar note was too fine-grained t

But this is just a question of granularity. When Zimbabwe hit hyperinflation they printed trillion-dollar notes because the 1-dollar note was too fine-grained to be feasible. Conversely, Britain used to circulate half-pennies, because there was a time when a penny was too large a unit to represent realistic transactions. In other words, as the world's wealth grows, won't we need a currency with greater range than "on a scale from 0-2,100 trillion, how valuable is X"?