Now that we are transitioning to B2C and P2P (C2C) globalized commerce, we need in some areas (especially intangible Internet commerce) a globalized unit-of-account and exchange.
It doesn't matter what the "unit-of-account and exchange" is, or whether it's globalized or not.
The trade value of an asset is independent of how it is measured.
I am ignoring you...
...because it is very costly store your cash flow in a unit-of-account which is not the predominant unit-of-exchange.
You go learn why. Learn about the cost of volatility. Learn why Germany's industry wanted the Euro to eliminate exchange rate risk for their European markets (and how that enslaved the PIIGS who borrowed in Euros but couldn't pay it back in devalued currency).
Please stop conflating investment with cash flow and running a business or your personal income and expenses.
The currency units that are used to measure that value are irrelevant.
Volatility is relevant. Those who have a unit-of-account which is the same as their unit-of-exchange, have 0 volatility exposure.
The higher the volatility, the greater the cost to hedge it.
There will be
only one currency.