Are there any other instances of this kind of issue to compare this against and see how it's going to play out. I'm trying to think of other instances where something was illegal at the federal level, and states have made that legal?
We haven't made it legal, just decriminalized consumption.
I did a debate on this topic 17 years ago. There are historical parallels though I don't recall the location of smaller regions legalizing marijuana within a larger nation. It's not all sunshine and roses when that happens: trafficking went up and crime stayed about the same. (from memory.)