China doesn't have a lot of debt. W inherited an annual surplus and a shrinking amount of long-term debt, and turned it into a huge deficit and greatly increased our long-term debt. W did not invest in infrastructure - unless you count expanding the military budget for the GWoT. Of course, while some of China's infrastructure spending was good (increased high speed rail), they also built ghost cities that sit empty. (Imagine Palin's bridge to nowhere expanded to be entire cities of "nowhere" where nobody lives)

for once the US stops selling them our jobs/oil gets costlier to extract/whatever

in many areas, our infrastructure is going to hell in a handbasket...and, Republicans have blocked efforts to set up a piddly little infrastructure bank.

breaks and lawsuits are factored in"

it's not opening until early next year, thanks to what appears to have been a plushly-funded media circus that quickly degenerated into race-baiting in the council chambers ...

No, I'm not in terror over internal stresses in the PRC.

Much of their manufacturing is outsourced European and American jobs and has as a cost a balance of payments deficit with Europe and the US. When Chinese manufacturing drops that could be from reduced domestic demand or reduced orders from the US and Europe. If the latter, that could be bad--expectations of reduced demand in those economies--or because manufacturing's moved elsewhere. Perhaps to Africa or SE Asia, perhaps returning to become domestic producting.

Moreover, reduced manufacturing there means less income for a command economy with very, very nationalistic views and increased military might to go along with those views. At the same time, it might make them a bit less capable of supporting the equally nationalistic but economically weaker Russia state.