In a piece titled "Why in the World Would You Own Bonds When...", Bridgewater (AUM: $150B) Founder and Co-CIO Ray Dalio outlines why he believes the world (and the US in particular) is in the final states of a long-term debt cycle, why that means bonds and cash are "trash", and how to think about positioning for what's to come. He notes: "The economics of investing in bonds (and most financial assets) has become stupid", and goes on to say:

The world is a) substantially overweighted in bonds (and other financial assets, especially US bonds) at the same time that b) governments (especially the US) are producing enormous amounts more debt and bonds and other debt assets. This is particularly true for US bonds.

Further, Dalio notes that there are over $75trillion in "US debt assets of varying maturities", and outlines how a "run on the bank" - an unstoppable wave of bond selling - can start, and what governments ultimately have to be do about it:

History and logic show that central banks, when faced with the supply/demand imbalance situation that would lead interest rates to rise to more than is desirable in light of economic circumstances, will print the money to buy bonds and create “yield curve controls” to put a cap on bond yields and will devalue cash. That makes cash terrible to own and great to borrow.

Dalio ends the article with a note on how policy makers may try and stem the flow out of bonds and into hard assets, and how the optimal portfolio for these times is no longer the traditional 'stock/bond mix':

If history and logic are to be a guide, policy makers who are short of money will raise taxes and won’t like these capital movements out of debt assets and into other storehold of wealth assets and other tax domains so they could very well impose prohibitions against capital movements to other assets (e.g., gold, Bitcoin, etc.) and other locations. These tax changes could be more shocking than expected.
I think this is the new paradigm.
For these reasons I believe a well-diversified portfolio of non-debt and non-dollar assets along with a short cash position is preferable to a traditional stock/bond mix that is heavily skewed to US dollars. I also believe that assets in the mature developed reserve currency countries will underperform the Asian (including Chinese) emerging countries’ markets. I also believe that one should be mindful of tax changes and the possibility of capital controls.