Like we have fiat currency digitally we also can have Fiat Currrency as paper.
I personally think its a good idea to have btc paper Currrency or metal coins too wich Will be accepted any shops!
Second point is that the dEvil is not the paper currency or any Kind of fiat currency the devil is the just the money printing out of thin air and lending this money out.
So nothing wrong with cash cash is not a devil!
If we implement this, we should just stick to the current system. Why spend billions of dollars just to do the same thing? Besides it is not worth doing given the risk stated by gentlemand. If the monetary system needs to advance, then just advance and leave the obsolete way behind. That way, we can avoid confusions and contradictions.