You can design a ideal token - the Platonic model of a crypto. Totally secure, totally anonymous. Assume it perfectly hides all information about all users.
And they could easily still destroy it - they'd just attack whoever offered cash for that token, who they would uncover by tracing regular cash (Dollars/Euros/Rinmenbi). There is no technical solution that can avoid actually avoid tracing when you turn the crypto into goods and services - unless both parties are willing to deal in that token exclusively AND not to keep records of any of their dealings. Which makes it only useful for illicit activities anyway - you're not going to get your kitchen remodel done and everyone is going to agree to get paid in your token and not report it to the government while also somehow hiding the fact that you're having people show up to your house to do work. It's just not practical. SOMEONE on the kitchen remodel team is going to go "Nah, I want...dollars?".
There's an XKCD about this:
^ They'd just drug the people involved and hit them with a wrench until they gave them the answers. Developing any of these "cryptos" is a total waste of time, and has been since day one - eventually people will figure this out and the price will plummet.
...in my opinion, obviously.
I think what's going to really happen is that the US is going to release a digital currency, and it will gain real adoption, and which one is Grandma going to use? Real US-backed E-bucks or... some trinket coin she doesn't understand that only allows her to buy heroin and contract killers? I mean maybe Grandma likes to party and has made a lifetime of enemies and it's a perfect fit, but I...doubt it?