You know what would really decimate the cartels? Decriminalizing drugs and treating addiction like the public health issue it is.
When someone who's addicted can go to a clinic and get clean needles and drugs of known quality they won't be buying it from street dealers, who in turn won't be buying from the cartels.
And let's not forget the American pharmaceutical companies who pushed opiates for decades in our own internal version of the British dumping opium in China. Can't blame those guys, though, because their drug cartels are all nice and legal.