They'll never ban alcohol again for several reasons
a) The government taxes it quite heavily, which brings in lots of money.
b) People woud never stand for it.
c)Traditionally, those substances assosciated with the poor classes have been heavily restricted, while those that are also used by the upper classes have been left alone. For example, marijuana was banned back in the days of segregation and racial discrimination, when it was mostly used by the evil, Black, jass musicians and their distreputable kind, and also by Mexican labourers. When in the 60s and 70s, middle-class white kids starting smoking it, the demcriminalization movement really got into full swing, to the point where it is now only a misdemenour in around 10 states.
The same is true to with crack cocaine. For the past 35 or so years, crack has carried with it a punishment 100 times greater than normail cocaine, despite being more or less equally harmful. Thats because crack is most commonly used by poor people and ethnic minorities, while cocaine is the drug of choice for rich, white America.
err, I'll stop my preaching now.