Drug sales are about turf. The more you control the more you sell. Dealers will not pack up shop if SHTF and there is no money. They will simply switch to whatever currency is being used, sex, guns, food and supplies. They will be trying to survive too. They also will not believe the collapse will last forever. When whatever gov rises out of the ashes the cartels will want to be in place. Maybe even negotiate into a new government position. Senior Cartel, Governor of Ciudad de Don Juan.