That changes nothing. They will just tell the miners to block those transactions, and threaten to confiscate their equipment if they don't.
Where are the miners?
The miners will generally be located in countries where electricity is abundant and cheap, the kind of countries who have all the incentives to sign a treaty promising to jointly enforce laws against cryptocurrencies.
What you want is the Jackboot of the state to punish those that will not bend to the desires of tyrants.
Thank Satoshi we have another way.
Satoshi left bitcoin in 2011. His "invention" was apparently not good enough for him to bother sticking around.