They would not go away, but they would have new names like R.J. Reynolds, Philip Morris, Safeway, Costco, Associated Grocers, Walgreens, Walmart, etc.
Cartels are just an efficient business model to control the production and sale of any commodity.
If marijuana were legalized, Mexican growers would have to compete with American farmers and they would lose, adios Mexican cartels.
Agreed. CA's medical marijuana program is an example. Business is absolutely booming. IIRC, I read that they made $1B in sales and collected $100M in taxes last year.
It's a known, high quality product and it's legal under CA law. It is nonsense to argue the cartels could compete against a market like that.