I thought most people here had heard of The Silk Road onion service: https://en.wikipedia.org/wiki/Silk_Road_%28marketplace%29
> An online bank could very well operate in the anonymous network because the traffic is already cryptographically signed, and users can enjoy strong authentication if they wish to or remain a pair of anonymous public/private keys.
Or you can use bitcoins to accomplish the same and you don't even need banks.
As William Gibson said, "The future is already here — it's just not very evenly distributed".