Some economists worry that China might eventually be mired in enormous debt
While any country can over stretch itself and find itself mired in unsustainable debt, it is hard not to roll one's eyes when one reads the report's really, really, really, remote scenarios for how China could get itself into such a situation. Given the current global geo-economic reality, spending as much time as the report does on the likelihood of this scenario coming to pass almost discredits the rest of what is actually a great report.
Chinese foreign reserves are almost US$4 trillion (as at September 2014) - more than the combined total foreign reserves held by the next 7 largest holders of foreign reserves (i.e.Japan, Saudi Arabia, Switzerland, Taiwan, Russia, Brazil and Republic of Korea). The United States foreign reserves, by comparison, are a paltry US$134 billion
At the other end of the scale, United States foreign debt stands at a staggering US$18 trillion - about US1 trillion of that borrowed from the Chinese - more than that of the United Kingdom and Germany combined.
The report then nonchalantly skims over the distinction between the mega-, giga-, tera- projects around the world and lumps them together as if they all pose the same systemic risks to each respective economy. This may serve the purpose of highlighting the manic pace of development taking place in China, but the author's US corollary to China's mega airports, rail infrastructure, city expansion, ports, malls, urban housing (albeit many of which still lie empty), are what I would call vanity mega-projects, such as the Joint Strike Fighter aircraft program, the International Space Station, etc.
If I were worried about a major global economy (and the US and China now the two largest economies in the world, by a long shot) "eventually being mired in enormous debt", it would be the one that is spending trillions of dollars on projects that cannot be used to further grow the country's economy in future. Spending billions on improving the county's economic efficiency (such as rail infrastructure, ports, airports, housing for migrant workers, renewable energy, manufacturing, education, etc.) cannot be equated to spending billions on improving the efficiency with which one can obliterate one's adversaries from the sky.