So explains Simon Johnson at Economix:

The G-20 is betting that China can keep its growth high enough to sustain the global economy while also not getting drawn into some sort of bubble — particularly one that would involve big Western banks. Given the nature of China and the volatility of global capital flows — international investors love you without limit, until the moment they leave you — this is quite a bet.
We should also not overestimate the ability of the Chinese government to fine-tune its economy. To be sure, the authorities have done well both in terms of high average growth and in terms of managing the effect of regional and global cycles over the last 20 years. Can they really do so well indefinitely?

I think the answer is no. But I’m also skeptical on Johnson’s broader prescription for far more debt-financed stimulus in the developed world.