Drugs are not legally available, like that, in any country that I'm aware of.
I have quite a lot of experience debating this issue. The first thing I ask is why current drug traffickers would stop selling the drug just because it had become legally available through some kind of a store, like a liquor store. They are all profiting right now. They are all selling higher potencies than what the government would probably release through a liquor store, so they would not stop selling just because there was another legal option. Unless there's some unwritten rule that I don't know about that they have all agreed to, it would not happen. You would just have more options—the legal and the illicit.