The problem you have is that relaxing of the laws has to happen gradually and simltaneously.
If one country or state or even town drops the drug laws, it gets overrun with the worst case scenario, as the very desperate flock to that region. The region then becomes a poster child for the 'I told you so's who will point at addicts, mess, and whatever external effects will come from that. If it is experimented and ends up in very public failure, the topic will be removed from discussion for a generation.
This is partially the case in Amsterdam, where most Dutch people wouldn't be seen in the red light district, as it is overrun with drug and sex tourists, usually from other countries. And do-gooders point to the Amsterdam red-light district and say 'see, do you want your town like that?', despite the fact that the laws are not Amsterdam specific, and apply to the country as a whole. And the rest of the country is a very pleasant place to be.
So you need to relax laws slowly and simultaneously, so that the problems can be dealt with as they arise, and successful health management can be introduced at the same time. And you have to take a very realistic view of the societal damage drug use can cause, no matter what type (ie beer or heroin).
Given these requirements, I can't see it ever happening in the foreseeable future, which pretty much guarantees the cartels will exist for a long time, possibly until they capture an entire nation and form an actual government.
EDIT: Just remembered a great line from the Ben Elton book (whose name I have forgotten) which is about removing drug laws.
The quote is something like : "Do you really care if another person becomes a heroin addict if it means your Grandma will not get mugged on the way home"
Really, it's all about people not trying to always rule and control the lives of others.
Yes, it's a safe city although late at night there can be some dodgy characters walking around looking for stoned tourists to relieve of cash whether by scam or by force.
Speak to a dutch person about going there, you'll soon understand what I mean. Most don't go anywhere near it. It's not that it's taboo, it's more that it is seriously uncool. Think about it - who hangs around in obviously touristy bars in their own city?
"Judging by every metric, decriminalization in Portugal has been a resounding success."
A couple of links for those interested in learning more:
http://www.time.com/time/health/article/0,8599,1893946,00.ht...
and
http://blogs.telegraph.co.uk/culture/tomchivers/100047485/po...
Legalizing drugs might throw them into chaos for a bit, but at this points it wouldn't be anything like a deathblow.
Well, we could start by not living in armed camps right on the edge of killing each other. Then a few disruptions won't have us escalating to death.
In Hobbes' state of nature life is solitary, poor, nasty, brutish, and short. We can stay away from that by living peacefully and cooperatively and respecting the rights of others. Social pressure, a reasonable set of laws with clear and reliable enforcement, and a code of polite consideration often suffices.
What is going on with the cartels is that organized crime has broken the delicate balance and the state of nature is returning. Organized crime isn't the only thing that can break the balance; famine or war are just as effective.
In this case, western society is suffering from a self-imposed wound. Those cartels are thriving on revenue from supplying people who want mostly benign consciousness-modifying substances. Usually that's a modestly profitable business (tobacco and beer companies make nice money) but not profitable enough to run a worldwide crime network.
Prohibition is a violation of the balance of peaceful society. A few people in society are demanding to control the mind and mental state of the rest by controlling chemicals. When they control the legal apparatus, the users of those chemicals need to buy them from a guerilla army that can evade the police. Prices rise enough to support a guerilla army of organized crime.
What exactly is there to do? Simple. Stop trying to control what substances people use to manage their consciousness.
Then we can end the violence, kidnapping, extorsion, and other side effects of guerilla conflict easily and move far away from the state of nature.