My self-question is, up to what point a successful launch of a digital Euro, versus a Digital Yuan and a Digital USD may increase the attractive of these currencies and thus could impact the exchange rate beyond the usual interest rates / inflation / import-export components of the demand for currencies.
We had digital Euro, USD and other currencies for decades. If you're using credit card, that's digital fiat currency. The only difference between these new projects and old systems is that now the government will be the owner of the network, so they won't have to request information from private companies. And if these digital currencies will be a public good, their fees might be lower than in privately owned payment systems.