I don’t know what kind of black market you envision in the future, but the present black market is all around you and most people don’t even see it… and the people working in the black market aren’t violence criminals. The black market is made up of private sales between individuals or small groups. The black market sales happen in private homes, out of the back of vehicles, or through private contractual agreements. If I don’t agree on the price, I am not forced to buy. Just like today, if someone rips-me-off, they will do it just once. I won’t be doing business with them in the future… and I will tell all my friends about how I got ripped-off. As for violence people, I don’t do business with them now, and I don’t expect to do business with them in the future.
(People involved in the black market may be defined as “criminals” because they are supplying goods and services the state does not want provided or these people are breaking state-run monopolies. Personally, I don’t see the crime in providing a service or product to a willing customer. See victimless crime: http://en.wikipedia.org/wiki/Victimless_crime.)
Trying to get raw milk for my family is how I learned about the virtues of the black market. I now happily shop in the black market wherever and whenever I want. If you want more information please read Food Freedom. See just how easy it is to be called an “criminal” by the modern nation state: http://eatkamloops.org/food-freedom-the-politics-of-food/.