What is mass? The black, unaccounted economy is 14% of GDP in the OESO countries, even here in the relatively well-behaved Netherlands it is 10% of GDP, or 60 billion €s for this tiny country alone. There's some mass there, and as far as I have been able to observe it, quite a bit of mainstream as well 8-).

Other than that, the state will always try to have a look at money flows, and they can always force one transaction as a starting point for digging: you pay taxes in the coin of the land, and that is enforcable. Also, cooperations couple addresses to payments, for transport purposes. Having an anonymous currency doesn't help much when cooperations open their books to government.

Things could go mainstream with the endorsement of banks and cooperations, but that won't happen without government having a look.

So no, I don't think so.