You're missing the point. It doesn't matter what the technology can do. There is a system that currently exists, and that system will protect itself through regulation. Cryptocurrencies will come within the fold or they will be outlawed. It is irrelevant what is technologically feasible. Governments and state actors don't exist in stasis, any advance in technology will be met with an appropriate response even if that response is "banks are not allowed to accept any funds that have any connection to X cryptocurrency." If that doesn't work, the response will be "banks are not allowed to accept any funds without perfect knowledge of the two parties transacting and where the cash is coming from." What bank would possibly risk going against the government? Even the well-known money laundering banks balk in the face of government scrutiny. What company would possibly risk losing their relationship with their bank?

Cryptocurrency fanatics think that they can digitally outcompete physical reality. They cannot. The governments of the world are the Borg - you will be assimilated.