Through out history, civilization has always had something popular it has outlawed, leading to years of conflict between society and the powers ruling over it. And often when the restrictions are moved, society changes to a new taboo fascination. Where am I going with this? As the laws concerning pot are gradually relaxed, what will take its place? What will people do to be rebels, and make a statement? Shrooms? Public nudity? Making american flag toilet paper? Pet ferret's in California? There are any number of fairly harmless things which subcultures could latch onto, and then let interest spread. But if you could figure out what the next thing will be, the options are limitless from being a cultural icon to just great marketing opportunities.
So, what do you think the next big illegal thing will be if pot is ever legalized?