Well, if the government can get its act together and grow some stuff with any real quality, or at least find a company that is willing to do it, I think that you'd see prices go down abd quality go up. If you can sell the stuff to Canadians for a reasonable price, and they don't have to worry about getting caught doing a drug deal, or killed by some drug related gang shooting, I think you'd see more people going towards the legal end.
The question is, why wouldn't you want to legalise it? What harm does it do? Because, unless you are going to outlaw alcohol, you already have just as potent a drug on the street. Not to mention that if you are going to make pot a more socially acceptable substance, I bet you'd see a decrease in people moving towards harder drugs simply because of the lack of the criminal element.
I should mention, though, that I have never done a drug in my life. So some of the stuff I've said might not be as accurate as I'd like.