Virtual currency certainly can be problem. Yet, the drug cartels continue to use the US printed currency. Why? My guess is that printed money is more convenience to the "work mules" at the bottom of the drug train. Cash doesn't leave many trails, but eCurrency is difficult to pay normal bills like rent, groceries or gasoline. Virtual currency requires a computer, accounts on both ends of the transactions. WiFi/cellular may become a issue too. But eCurrency needs time to mature like PayPal or Google Pay. If there is a way, there will be those who will try to find "the way."