Not very long, 50 year since Brettonwood break.

Since Brettonwood break up:

Gold: 1400/35 = 40

Stock: 12000/800 = 15

In gold standard, stock wins but why? Because only then, the investment return is more meanful at a stable currency environment.

Will we return to gold standard? I do not know. The history only says human tried any other standards and failed, then they return to gold standard from time to time, even very short period of time. 

That is why our founding father say, the money needs to be in gold and silver. But they know politicians and financiers will try every way to abolish that because the only one gains is the one who have access to the money creation, such as FED and whatever behind it.

And that is why Thomas Jefferson said:

I believe that banking institutions are more dangerous to our liberties than standing armies. If the American people ever allow private banks to control the issue of their currency, first by inflation, then by deflation, the banks and corporations that will grow up around [the banks] will deprive the people of all property until their children wake-up homeless on the continent their fathers conquered. The issuing power should be taken from the banks and restored to the people, to whom it properly belongs.

Thomas Jefferson, (Attributed)
3rd president of US (1743 - 1826)