All of these mind altering drugs are here and abused now. If not the exact ones, very close to it. Lets go down the list of things that will fry your brain. Meth, Klonopin, Xanax, Percocet, Valium, Quaaludes if you were so lucky to still find them, Hydrocodone, Lortabs, etc. The drug use and abuse will not become any more prevalent than it already is. The difference is the strains will be pure, the location to pick it up and use it will be mapped out and the fight will have tax dollars generated by its sells to combat it. Check some of the countries that have opened up the drugs to all and see that it didn't make the world stop. People know where to go and know where not to. I have some European buddies that have taken their kids (in the daytime of course) down some of the bad sides of town to show them junkies, dead with needles still in their arms.
Currently, we are chasing our tails with the drug crisis and there is no return on investment. Fund it with the people that are the problem and know where they are. Otherwise, you are chasing a needle in a haystack trying to find the drugs to begin with, then there is no budget to actually fight it when you find it.
That is a pipe dream though. MJ probably won't be legalized in Alabama for another 25 years. Real drugs will never be legalized in my lifetime unless there is an overthrow of the government and some 70's rock bands become the central driving force of our government.