By comparison, the above mentioned BTC allegedly used for illegal activities only sums up to more than $ 9.79 billion and its almost traceable!
Now a recent statistics shows a frightening amount of more than $ 232 billion (see link below) on illegal drugs spending alone and we have to consider that most of these transactions were made possible by using fiat money which is almost untraceable.
Now if those BTC hits the market, which I assume is happening right now, I think it doesn't have a big impact if we ought to compare it to illegal transactions using fiat money. Imho.
Source:
https://www.worldometers.info/drugs/