If drug dealers aren't an issue, you know-because they are non violent, than as more and more of the marijuana supply is legalized (or conversely the illegal supply is diminished) we should see a decrease in marijuana convictions, and crime overall.
But we wont-we already know criminals simply move into other areas.
“I think if Thomas Jefferson were looking down, the author of the Bill of Rights, on what’s being proposed here, he’d agree with it. He would agree that the First Amendment cannot be absolute.” - Chuck Schumer (D). Yet, Madison and Mason wrote the Bill of Rights, according to Sheila Jackson Lee, 400 years ago. Yup, it's a fact.