More specifically it was not a substitute but assumed the workings of Bitcoin with the Blockchain web.
There are already numerous exchanges that make the coins comparable to FIAT circulating in the real globe, for example, true USD, USD Coin, Tether aka USDT, Gemini Dollar, and bitUSD. But maybe in the very distant future, it may be yes, but shortly, it is unlikely because there are a lot of corners on earth where there is neither electricity nor devices to use cryptocurrency!