The problem with all of this is portability and traceability.
If I buy $10,000 of bitcoins, and I move that money to a bank in the Cayman’s then there is a digital footprint of that transaction.
That is why bitcoin will never replace hard currency or precious metals.
While I may not leave the US with more than $10k in currency without declaring it, it doesn’t stop me from moving it in smaller quantities.
And how much could you transfer in gold behind a belt buckle?
If I take $100,000 of bitcoin on a USB drive to the Cayman Islands, no one will know. Do that with hard currency.