The Decred community is currently discussing a proposal for its Treasury to fund the development of decentralized exchange infrastructure.
Jake Yocom-Piatt, Decred’s lead organizer, first proposed this kind of exchange in a blog post in June 2018. Since then the idea has regularly been the subject of discussion within the community — it even has its own chat channel.
The proposal’s rationale is that tooling and infrastructure for permissionless exchange of cryptocurrencies augments their utility. With the appropriate tools, exchange intermediaries (and their fees) can be avoided altogether. The problem is that there is no incentive for anyone to build such infrastructure without incorporating a method through which they would profit.