Thats a good thought about the bitcoin and fiat tie up but there are again few more questions that arises. I mean why government will choose bitcoin for this purpose and why they cant just go and rule out the cash itself? So that by declaring that they will be using only digital forms of payments ? They can always do that and same thing is happening in country like India. Where to stop the money laundering they literally changed the currencies throughout the country and declared that use of digital payment will be rewarded. The results were pretty good and I guess its worth to think that government can control it the way they want.