This is unenforceable. Some of the relevant open source projects are being developed by contributors based outside the US who have no possibility of knowing whether the address receiving coins in a transaction is controlled by someone based in the US. It's not even possible within the design of bitcoin and related cryptocurrencies for developers to add such tracking provisions, since the generation of an address is algorithmic and can be done with pen and paper. If indeed the law is as the EFF describes it, it must have been written by someone with zero technical knowledge about cryptocurrency. This is not a viable regulatory approach. The implementation is not cognizable -- and therefore is not enforceable.