[wruza]

As long as there's a critical mass of users somewhere

All that mass lives in EU, US and China, and nowhere else, that’s where the argument breaks down. You can buy a nice rc toy with bitcoin, but some day you may need a place to live in and they will ask you where you got the money from. And you’ll say, ah, that’s from that illegal btc exchange.

[__MatrixMan__]

Do you think that there will be some kind of fiscal big bang in the future where all legitimate money stops being fungible? A point after which holding a dollar means holding something that can be traced back to that moment and shown to be held by one of the good guys? Because that's what it would take, and I just don't think the governments can pull it off. To say that one group of people's money/saleable property matters and the other group's doesn't--it smells too much like the creation of an aristocracy to get the masses to put up with it.

As long as you're willing to pay taxes on it as income when you bring it back into whatever system banned it, or whatever system replaced that one, you're going to be able to do it.