I lost confidence in Bloomberg ever since they came out with that BS piece about Chinese "spy chips" in servers. Everyone in the trade industry shot them down for it.
With regards to sources for minerals, iron isn't particularly scarce to begin with, it is one of the most common metals in the planet. It is also usually easy to recycle so China can easily upkeep their own societal standards even if they did not import anymore. China also has a huge opportunity just next door. Mongolia is open for mining business after centuries where mining activities were forbidden for religious reasons. A veritable treasure trove just next door and close to where much of Chinese heavy industry is.
With regards to China's alleged construction binge it still isn't the end. China did very smart investments in building more dense city areas which mean they will need a lot less energy per capita to achieve the same high living standards. The high speed rail, subway, etc, construction together with high and mid rises were all good bets at the time. China has recently capped construction of further high rises to increase cost effectiveness and there are still a lot of improvements to build in cleaner energy, clean water, sanitation, etc.