According to the numbers above a bitcoin transaction is currently 591715 times as expensive (in kwh) as a visa transaction.
If a transaction costs half as much power every 4 years that's only 193 years until it's cheaper than visa[0]! Truly the financial instrument of the (distant) future!
[0] https://www.wolframalpha.com/input/?i=x%5E2+%3D+%281005%2F%2...