The hard part for these marketplaces will be building and establishing trust online. Complete anonymity will be counter-productive for legitimate businesses.

When we think of the internet there is both the good and the bad coexisting. At first people would have spelled doom for the internet because of all the evil it could be used for. I don't see why a similar paradigm cannot exist for these decentralised online marketplaces.

particl.io looks interesting. I will check it out some more.