Look at California for just a taste of how it could be. Cartels can't push their outdoor mass produced garbage marijuana in Cali when anyone over 18 can walk into a Doctor's office, get a recommendation card, walk a few feet to the dispensary next door, and receive the most quality indoor, top-shelf, out of bounds Cannabis you could buy. This is decidedly not your father's lid of smoke in a sandwich baggie licked shut. The Cannabis has often been tested for anything from potency (THC and cannabinoid or CBD count) to contaminants. Some 3rd parties are actually certifying Organic Cannabis.
Most of that top-shelf Cannabis comes from multi-generational farms in the Emerald Triangle of Northern California (Mendocino, Humboldt, and Trinity). They have farmers who have passed down seed and clones from generation to generation, along with their breeding, growing, and flowering trade secrets.
Cartels only know bulk pricing and murder. More legitimized drug trade will not only lower cost and increase quality, but would make Cartels seek other forms as their profit margins evaporate. I'd love to see even the biggest cartels try to compete with Anheuser-Busch InBev, Pfizer, or Altria group once Marijuana is legal in the US.