If a drug addict, alcoholic, smoker was In a comer for 12 months - would he crave on waking up?

First of all, the most dangerous drugs to come off of are alcohol and benzodiazepines. Heroin and Morphine addiction is very severe but they are less wide spread than alcohol and benzodiazepine addiction. You cannot die withdrawing from heroin or morphine. You may feel like you want to die, but death as a direct cause of withdrawal from these two drugs is not possible. You may vomit and choke on your vomit, but this would be asphyxiation. You can literally die from quitting alcohol or benzodiazepines as a direct cause from the withdrawal process.

Secondly, no private clinic in the world would ever put someone in a medically induced coma, especially, for that long to over come addiction. There are many reasons for this. The first is that it simply would not work. This is because no matter how long an addict/alcoholic is clean/sober there is a phenomena of craving. This has been proving in PET scans that chart the brain function when an addict/alcoholic has a craving. You can have 20 years clean/sober and still relapse because you have such an intense craving for the drug. No one understands why these craving occur, especially after such a long time without the drug. The second reason they would not do this is because there are proven methods that can detox and rehabilitate someone without literally putting their life on hold for a year. These methods involve cognitive behavioral therapy and talk therapy and sometimes medications, none of these methods would work if a person was in a coma. The third reason this would not happen is that even at private clinics, doctors still have a set of medical conditions they have to live up to or they can be sued for malpractice, have their license taken away, and even be jailed for negligent homicide. The fourth reason this would never happen is because it only take 2-14 days to get most people detoxed form a drug. This alleviates their physical dependence on the drug. After this it is a psychological dependence which must be treated with meetings, therapy, and medication.

And lastly, the problem with you list is that only 2.1 million people in the US admit to "sometimes" using heroin. Many studies say nicotine is more addictive than heroin. Many people will die of their addiction to nicotine. Alcohol is the number one killer among all drugs. Yes, coming off of heroin is ugly, but if you ever want to see something very ugly, watch a long time alcoholic come off alcohol. Delirium tremens, loss of all bowel control, panic attacks, auditory and visual hallucinations, paranoia, shakes, confusion, panic attacks, seizures, heart attacks, death and "wet brain".

I don't believe so, since the body is functioning for long without the substance the cravings would subside. However, inducing comas for that long is really costly, as well as dangerous, as there can be no guarantee that they would wake up at all.

By that point the body would not "need" the drug, but the user would still crave them all for the effects.