Amazon has taken one of several steps toward what I presume is a vision for a global currency. Amazon Coins are:
... a new virtual currency for U.S. customers to purchase apps, games, and in-app items on Kindle Fire.
Pair this with Amazon's patent on a digital second hand market, add Bezos' famed long-term view of running Amazon, Amazon's already gigantic scale and its intersection with physical and digital goods and, well, looks like a duck, walks like a duck ...
[Update: Dec 2017. That didn't play out.]