If a digital currency replaced a fiat currency, wouldn't it then in fact be fiat?
Depends what you mean by fiat. The word itself means "not voluntary", but in the context of economics, it is taken to mean "a virtual (valueless) currency" because those are the currencies that people will not use by choice.
Bitcoin is new. It is a fully virtual currency, but not one that anyone is being forced to use. Kinda hard to call that fiat. We need a new word to describe it.
Fiat: A Latin word meaning let it be done
Currencies can be classified into two monetary systems: fiat money and commodity money.--wikip
"Fiat money" is money that's not backed by a physical commodity, e.g. precious metals. It is typically backed by governments,
Bitcoin's not backed by physical commodities. Nor is it backed by governments, so yah, it's sorta hard to call it fiat.
Or "currency," for that matter
