Well, the cause of death for someone dying from their addiction is not always "drug overdose", but things like accident, murder, or suicide, which in fact are the top three causes of death for young adults.
I find troublesome that the author of the article (renowned neuroscientist and addiction journalist as cited) suggests that addiction is akin to a habit. The behavior itself is certainly habit, but the addiction lies moreso in the etymology and function of the habit than the actual repetitive behavior. For some, the addiction is distraction, for some escape, for others a sense of identity, and so on and so forth. To prescribe "outgrowing the addiction" as a solution is awfully simplistic, almost suggesting that if an addict could only replace that habit with something else, then all would be hunky dory. Well, in theory, sure. Maybe we can start designing rehab centers like they used to do traffic school - Improv Traffic School, Comedy Traffic School, Bikers' Traffic School - maybe Knitters Rehab: "We'll help you put down that needle, and pick up this one!" or Foodies Rehab: "Stop smoking that joint, and learn to smoke these ribs!" The possibilities are endless. But not likely.