Decriminalization of all drugs by the U.S. would be a major positive step away from the war on drugs.
The paradox of the war on drugs is that the harder governments push the fight, the higher drug prices become to compensate for the greater risks. That leads to larger profits for traffickers who avoid being punished. This is why larger drug gangs often benefit from a tougher war on drugs, especially if the war mainly targets small-fry dealers and not the major drug gangs. Moreover, to the extent that a more aggressive war on drugs leads dealers to respond with higher levels of violence and corruption, an increase in enforcement can exacerbate the costs imposed on society.
Taxing legal production would eliminate the advantage that violent criminals have in the current marketplace.