http://www.wired.co.uk/article/mr-bitcoin-nfc-implantA scientists made a BTC implant that goes into back of hand.
Human implants function most "effectively" when they are implanted in the back of right hand or in the forehead. Now take a look at the bible
"Revelation 13:16-17King James Version (KJV)
16 And he causeth all, both small and great, rich and poor, free and bond, to receive a mark in their right hand, or in their foreheads:
17 And that no man might buy or sell, save he that had the mark, or the name of the beast, or the number of his name."
Currency involving gold and silver were phased out and replaced with fiat. Wasn't it obvious that once computers and the internet came about that digital currency would emerge at some point in time? But what comes after digital currency? Implants! People prefer convenience over almost everything now days. There is no doubt that electronic implants will be made mandatory at some point in the future after both fiat and "traditional" cryptocurrencies have been phased out.