The future will catch up with fiat currency when people will appreciate digital currency such as bitcoin more than the fiat currency we have around. I believe digital currency and fiat currency can coexist in any economy in the world.
In the next decade digital currencies are increasingly being used for transactions and investments. However, replacing fiat money is clearly not possible, because for digital currency applications, fast and stable internet technology is needed. Until now not all countries have that technology. As an alternative, bitcoin payments provide added value that benefits all parties because it is faster and cheaper.