I believe that there will be a digital currency that will become the transaction currency in life. It is best to unify the currency and no longer have various exchange rates. Really been waiting
Not happening, whether you are talking about the market of cryptocurrencies or fiat I doubt a single currency will emerge as the sole winner and have no competition at all from other currencies, and this is because there are simply too many interests around the world which prevent this from happening, so in the fiat market even if the US dollar is the dominant currency, there are other currencies which will always compete against it, and there is even a concerted effort by some countries to try get the dollar out of that position of privilege.