So, this time instead of gold we will have Bitcoin (which will be hoarded as per Gresham's law) and all kinds of "paper" derivatives inevitably entering the circulation as a means of exchange. These "papers" allegedly backed up by Bitcoin will in fact leave behind them only inflation, even despite Bitcoin intrinsic deflationary nature...
And welcome back to fiat!
You say instead of gold we will have Bitcoin.
Has gold failed?
Yes, it has failed as a currency, and later as an asset backing up a currency. The said doesn't mean that its price dropped as it actually has increased over time with the dollar constantly depreciating. Gold surely didn't fail as a store of value. Personally, I would go for a tighter definition of currency that assigns more significance to it as a means of exchange before anything else...