It's obvious that you're trolling, but just in case you're not: Eventually you can expect a push against cash in the name of anti-terrorism and anti-crime campaigns. Obviously those will be founded in bull-shit but that's not going to stop it from happening. Whether or not it will succeed is mostly a matter of how it gets sold to the public.

As for how it is possible for all of the available currency to be contaminated with traces of drugs and yet that this does not need to prove that all (or even a majority) of the cash transactions done are drug related, I'm sure you're smart enough to figure that one out for yourself, but evidence such as this will figure prominently in the kind of discussion that will visit us some years into the future.