Structurally, China has never restructured its economy or its systems. Tinkered, yes. Restructured, no.
It does not, for example, have proper insolvency or bankruptcy laws in place (ie: as a measure of protection for creditors).
The gulf between rural (especially, in the western provinces) and urban (especially the south east coastal provinces) is enormous, and growing.
As for the N-E industrial belt, this is increasingly reflecting the state of East Germany immediately prior to reunification.
Most commentators also ignore that China is made up of a number of different cultures /languages /ethnic mixes. This in itself risks rising domestic tensions.
With non-performing loans through State Banks estimated at 40% of GDP, and a growing Government deficit (with high tax leakage and poor collection coverage), China has more than a few challenges ahead of itself.