DEXes on the other hand have no way of integration with the fiat system because no bank or government would ever do that willingly, at least not in the near future. And since DEXes they cannot send or receive fiat money, they cannot really do any conversion between crypto and fiat.
Well, DEXes in its pure form are only platforms to provide an exchange means between users. So there is either no platform operator (in a P2P system like Bisq) or the platform operator controls some kind of DAO which takes some decisions regarding protocol configuration.
So there isn't really a straightforward way for bank to "support" DEXes. In general it's the individual users which simply operate their bank accounts, like when they're buying and selling things on an ebay/amazon style marketplace.
There are two ways I could imagine how a crypto-friendly bank could improve the support for DEXes:
- a quite simple one: add a digital signature to documents providing a proof for a transaction. This should normally quite straightforward and it is even possible some banks already offer it. It would enable people to prove they send a fiat transaction.
- a more advanced one: the bank could run an own blockchain with an USD, EUR, BRL ... stablecoin. A Brazilian exchange has done something similar but they aren't a full bank; they however provide an IBAN-like bank transfer account and allow the exchange of some South American currencies to a blockchain-based stablecoin token, and this stablecoin can then be freely used in DEXes. However,as they are also operating a crypto exchange, there is not really an advantage to use a DEX in this case.
IMHO the best that a DEX could do in that respect is to provide a distributed version of LocalBitcoins/LocalCoinSwap/etc. [...] Actually I think that if someone develops a DEX that supports all these features plus all the features of existing DEXes, including the ability to make atomic crypto <-> crypto swaps, that would be a great system.
I would love it if atomic swaps are integrated into Bisq. I would also love fiat <-> altcoin trades which could be used for micro-refills (e.g. buy 5-10$ of crypto) where the scam risk is extremely low.
AFAIK Bisq 2 which is currently being rolled out can support different exchange mechanisms, so it's possible they could add such features in the near future.