In reality, if this happen; it will displace Amazon and other giant in the middleman business. A decentralize market place will put the middleman into check which is unavailable at the moment but with the help of the Blockchain technology there will be a freedom for all. The advent of Blockchain acceptance and adoption will put all the big wings out of the business.
I'd go along with that. Amazon is really a society cancer, i think that sooner of later, Amazon will be kicked out of decentralized marketplaces.