Stablecoin is a type of crypto currency either on ERC20 like USDT or on own mainnet such as Libra. Since we already have fiat currency like USD and EUR, why need stable coin to make mapping to them.
My view is “Stable coin serves as oracle machine for fiat into blockchain world”. Oracle machine is an idea in smart contract that it brings real world information into blockchain consensus world. It is very difficult to build oracle for many real objects such as weather and time, but stable coin is a great oracle machine, run by financial organization, to map fiat into blockchain.
Blockchain coin will eventually win fiat and take over the world, the consensused relationship between coin to fiat is done through stablecoin. The stronger operation stable coin established, the easier for coins such as bitcoin to show the long term winning advantage to fiat. The above chart shows that a powerful stable USDT serves as a “short tool” for bitcoin owners.
Libra will be stronger than USDT since it is powered by facebook. USDT is a relatively small operation. I wish more and more major financial orgnaization to issue stable coins reflecting how much inflation in it, so that real crypto currency like bitcoin can establish more strong winning relationship to fiat through these stable coin oracles.