Well I think that many will use bitcoin for selling illegal drugs related because of it's anonymity. They will continue to use it because people using it is hard to track. That way bitcoin will be branded as drug money by many.
What do you think is harder to track? The $50 note you got from a friend of a friend, who bought a hotdog at a street vendor, and now you used it to buy a bundle of weed OR the $50 worth of bitcoin you bought from a exchange linked to your bank account or from a stranger < possibly a cop? > on localbitcoin or even the service you used online, that collects all IP addresses?
Think again, if Bitcoin is more anonymous than fiat cash? If I smoked some weed, I would rather buy it with cash.