I think that we should have a global virtual marketplace for cryptocurrencies without any intermediaries. This would lower the costs of transactions and decentralize the market. What do you think? Is that possible? What are the benefits?
I think there are several that are already trying to make this happen. But none yet that is noticeable enough that people can actually use in order to substitute a central marketplace. Also, I believe that decentralizing the market, and decentralizing the middleman (or just completely eliminating it) are two different things.
To be honest, I don't think that such a middleman-less marketplace is needed right now. There are p2p sites for advertising, like Craigslist, but I wouldn't say that constitutes a "marketplace".
What matters most is the cryptocurrencies themselves staying without a central entity, which is something that we're seeing people are shifting away from. If the crypto itself and the money creation process, and the transaction settlement process isn't decentralized, then there isn't really any point in trying to decentralize marketplaces.