We're never going to "run out of oil." We're going to get to a condition where oil is scarce and expensive.  Oil can be diverted from civilian to military use with alternative fuels and fuel additives stretching the supply.  How much and at what cost ain't my gig, hopefully someone who knows will jump in.  :-)

The US government has never been shy about grabbing natural resources and given the fact China has to import oil using the sea lanes I think it's reasonable to assume the US Navy would interdict and confiscate, i.e., steal, oil shipments in a shooting war.  In "peace" (ha-ha-ha) China depends on US and, increasingly, European consumers to buy their Junk and, increasingly, US and European consumers cannot afford to.  

I wholeheartedly agree "this era cannot last."  Reality will, in the long run, Win.  I'll guess there are discussions happening in the Pentagon and other country's military planning departments but I'm not privy to those discussions, so ... what do I know? How TPTB and their armed thugs will respond remains to be seen.

She believed in nothing; only her skepticism kept her from being an atheist. -- Jean-Paul Sartre