Currency is merely one investigative method. There are plenty of others and like all crypto systems there will be cracks, people will make OPSEC mistakes, and ultimately law enforcement agencies have access to hacking&#x2F;CNE.<p>Additionally, the money by itself may be anonymous, but that person will have to convert it to other currency or make purchases. Those purchases may be physical objects like cars, or rent, or any other large purchase which the person will have to demonstrate how they could afford to purchase it. The IRS would still be able to detect irregularities in consumption.<p>If anything it will be a boone for the information security industry, they will have to stop selling snakeoil and start selling solutions that actually prevent peoples money from being stolen.