If openbazaar succeeds in creating a robust decentralised platform for trade, the portion of black market transactions done in bitcoin will grow significantly, and anyone holding bitcoin (eg. a16z) will get big returns.
The black market is already well established on Tor, so I'm not sure if OpenBazaar will result in growth in such markets, or just a shifting of some existing business from Tor to OpenBazaar.
It is well established, but plagued by issues relating to centralisation - exit scammers, law enforcement infiltrating markets, people stealing bitcoins. Each time this happens, growth is damped as buyers and sellers shuffle over to new operators. OpenBazaar would revolutionize this.
