Your challenge is to have China face a large financial collapse by 2015 (2013-2015 is the time period I'm looking for), and have it be within reason. Mega bonus points if it doesn't entangle the US much or at all in the downturn.
Having a Chinese financial collapse be an already acknowledged fact instead of 'I think it is happening if you kind of squint' won't be that hard. Have someone/organisation in China start a panic earlier, say with real-estate speculation triggering a collapse because local governments are supposedly heavily dependent on real estate sales for financing.
Not having it entangle the US?
Have the country so much manufacturing/final assembly has been shifted to disappear up its own smoke stack and have it NOT affect the US?
Good luck with that. I can see where the Mega bonus points come from.
It would be easier to go the other way and have The Great Depression/Dark Ages - The Sequel!!! - triggered by it instead. Possibly with a Chinese Civil War fought with Nuclear, Biological and Chemical Weapons, ecosystem collapse, nuking of nuclear power plants and chemical factories leading to mutant zombie armies roaming the steppe towards Europe with Putin denying anything is wrong while tossing more NBC warheads at them, green glowing mutant Panda Bears roaming the deserted city streets armed with AK-47's and RPG-7's...
Sorry, got carried away. I wouldn't rate that as having a more than 50/50 chance of happening by 2020 anyway so not to worry. Though I keep thinking about writing that Timeline, it sounds interesting, in the curse sense.
No I haven't taken my medication in some time, why do you ask?