One would think that they'd start moving to technologies that are decentralized using technologies such as distributed hash tables. This puts the onus on the users to have a client app that helps host the transaction system for everyone else.

The clients would openly share the buy and sell orders and then communication would moved to an encrypted channel that supports perfect forward secrecy.

The only part that ostensibly needs to be centralized is a ledger maintaining the reputation tied to some pseudonym.

i.e. the identity of DPR is passed along to all the users of the site collectively.