No. not fast enough to function as a single currency because not all countries around the world has not supported it yet. Bitcoin is not yet mainstream and not enough exposure as well. People are afraid because bitcoin is not "physical" not like gold or fiat. Although bitcoin is gaining a lot of supporters in some countries, is not fast enough to be considered to function as a single crypto-currency at the moment.
Yes bitcoins is that fast enough to function as a single currency
Ya it is not a mainstream now but by seeing the growth rate of our technology we can say that in a decade or 2 decade bitcoins can function as a single currency
If everyone gets to know the profit in investing in bitcoins tgen they would obviously turn up fiats and start using bitcoins
As we see bitcoins has a great potential,
But for starting this all the companies should start accepting bitcoins, so that we can shop with our bitcoins
We need to globalise this crypto currency, people should know that though bitcoins are not like fiats physical but they are safe