John Hussman expects US shares to fall 66% - and so do others

In this article, highly regarded US hedge fund manager says "I expect the S&P 500 to lose approximately two-thirds of its value over the completion of this market cycle." Mind you:

from these sort of levels using Shiller's straight cyclically adjusted P/Es, US shares fell 89% from they 1929 peak, 67% in real terms from their 1968 peak, 60% after the 2000 dot com bubble before the US Fed pumped the bubble up again to the 2007 peak from which it fell 53% (making the fall in real terms from March 2000 to March 2009 62% in total). So I think Professor Robert Shiller would also be comfortable with John Hussman's forecast decline for US shares.
Famous fund manager and bubble researcher Jeremy Grantham from memory, believes that fair value for the US S&P500 is below 1000 - meaning that a decline of more than 60% would be required to bring it back to fair value.
GMO (of which Jeremy Grantham was a founder) is currently forecasting for US stocks over the next 7 years an average real return of -4.7%pa. (i.e. a 30% fall in real terms over the next 7 years). See that forecast at the following link.
https://www.advisorperspectives.com/commentaries/2018/02/02/7-year-asset-class-forecasts?
And Elliott Wave International (and Robert Prechter) are expecting the end of the credit cycle that commenced with the 1930s Great Depression to commence "soon", and with that possibly a fall substantially bigger than the what John Hussman is forecasting.

So John Hussman is not alone amoung "old hands" in the financial world to hold such a bearish 10-year view for US shares. https://www.advisorperspectives.com/commentaries/2018/01/30/measuring-the-bubble

John Hussman's US share market valuation model suggests that US shares are now more expensive on broad average than they were at the peak of the dot com boom in March 2000.