I have been watching with interest this video by the 'Grumpy Economist' John Cochrane on the sustainability of the US Debt:

https://www.youtube.com/watch?v=bV_beNSQ4_U

I find this analysis thorough, but I agree only to a point. First of all, the idea that the 'Markets' at some point would demand higher interests on US bonds fails to understand some important facts of the Money system. Specifically, agents hold US Bonds not solely with an 'investor' mindset. US Bonds are used as the World reserve currency and are the vital liquidity of the international money system (e.g. the Eurobonds markets). I would argue that most agents demand US Bonds for all reasons but investment. As such, they are little sensitive to the level of interest rates or the overall US debt. In short, as long as the US Dollar retains the credibility to be the World reserve currency, the US Debt can grow 'safely'. 

A second point, we need to take a more critical look at the corporate sector and not blame the government for all problems. The pursuit of short term profit by public corporations has done far more damage to profitability than any government regulations. Besides, much US regulatory body remain extremely corporate friendly thanks to the legalization of corporate brib ..., ahem, lobbying (Citizens United). Let's look critically at the whole concept of Shareholders Value maximization, which has caused companies to take all kinds of shortcuts in order to chase Wall Street consensus. And in doing so CEOs have gutted once phenomenal companies. This situation cannot be changed simply with a different government fiscal policy or 'less regulation'. 

The growth of the US debt is a symptom, not the cause, of decaying economic system where 'rent' seeking has taken over 'productivity' seeking. This is normal late cycle economic evolution and human nature. Let's put more history into the study of economics.