While I agree, all of the ways you mentioned to pay for something are fundamentally something that requires infrastructure to create (industrial, banking, or a mint), and has a physical anchor that can be plucked from you by physical force (including the SWIFT transfer - though usually bank's prefer to comply than shut themselves down).
A blockchain based currency will exist as long as there's someone with a sufficiently powerful computing device connected to a sufficiently low-risk network that can be accessed legally or illicitly. A blockchain wallet will exist and be yours alone as long as you keep the password in your brain, never write it down, and resist attempts to extract it from you.
This means that, in comparison to conventional currency (including Nuka-Cola caps), a blockchain economy is much easier to operate undercover when it's outlawed.
A blockchain based currency will exist as long as there's someone with a sufficiently powerful computing device connected to a sufficiently low-risk network that can be accessed legally or illicitly. A blockchain wallet will exist and be yours alone as long as you keep the password in your brain, never write it down, and resist attempts to extract it from you.
This means that, in comparison to conventional currency (including Nuka-Cola caps), a blockchain economy is much easier to operate undercover when it's outlawed.