Centralized exchanges are one of the main single points of failure of the cryptocurrency ecosystem. There are alternatives, but they are cumbersome (OTC cash-to-BTC trading) or risky (trading on this forum, for example).
Current cross-chain DEX based on atomic swaps do not include the possibility to purchase Bitcoin with fiat, for obvious reasons (there simply is no such a thing like a "fiat blockchain").
Now, there is a
decentralized exchange tool that allows fiat-to-crypto trades,
Bisq. Bisq has, however, one problem: A fiat-to-BTC trade has always some volatility risk. Both traders must deposit Bitcoins and the price could go down, and as a Bisq trade can take some time, the risk for losses is relatively high, specifically in price downtrends. "Hodlers" and crypto veterans may have no problem with this, but for the general public it may be too risky. At the other hand, there is a certain risk that the trade is cancelled by the "fiat party" when price goes down sharply and the security deposit is too low.
Both effects are, in my opinion, reasons why Bisq's volume is very low at this moment.
Now what if the cryptocurrency you want to trade your fiat to is a
stablecoin and isn't volatile, or even pegged to your fiat currency? For example, you could trade 1 USD to 1 Dai (Makerdao's USD-pegged stablecoin) or 1 EUR to 1 BitEUR, without having to even negotiate a price. You could be (almost) sure that you'll get the "correct" price.
Current Stablecoins (look
here for a list) are not perfect, because there could be black swan events where they lose value rapidly, but the probability for this to occur in the typical timeframe you carry out a trade is extremely low.
Now you could "extend" a Bisq-like "fiat-to-stablecoin exchange" to an atomic swap-based DEX like BarterDEX. So after you purchased a Stablecoin in Bisq-like fashion, you could then carry out an atomic swap, buying Bitcoins or your desired cryptocurrency for the stablecoin. As Bisq and BarterDEX, for example, are open source, all could happen in one single client (using code from both projects) and with few clicks.
So in this case we'd have a complete decentralized replacement for centralized exchanges. A trade would need some hours to complete, but not more then a typical trade on a centralized exchange including the time for the bank wire.
The stablecoin integration in the exchange tool would also be useful if you want to simply escape cryptocurrency volatility for some time - like many people do now on centralized exchanges, risking the owner to get hacked or running away with the money. One problem less ...
What do you think? Discuss!
(Edit: Edited - only the fiat party can really cancel trades, and it's a breach of the contract. But nevertheless there is always volatility risk because Bisq involves Bitcoin deposits by both parties.)