Lets suppose someone moved to china, involved and established in microstock. Are there any factors that would stop them from being successful?

You're surround by Chinese models, and the Chinese are not particularly known for respecting copyright, so your main market would probably steal your work.

If there are problems, are their workarounds? What would it take to make a successful living from a place like China?

I suppose knowing the Chinese (Mandarin) language would be quite helpful
Workaround: hiring an interpreter
Can you speak / read Chinese?

China has 7400 + km high speed rail, and looks to expand it  to 16 000 km by 2020, which  means they probably finish sooner. China is the future, their cities will be center of commerce, shopping, entertainment you name it, the places everyone wants to go to live. I have a friend teaching english there, and he always notes me I should go there if I like shooting nice gals, because chinese girls in the cities are dam' cute, very body conscious, you can walk all day without seeing a single girl who isn't slender (opposite of usa), and they gladly model just for pics.

Probably a little off topic since the OP cares about payouts and not the actual buyer market in china since i dont think there is a large enough market yet. In 5 years, i think there will be.

Are there enough content creators right now in china? Is the chinese government making money off them? taxes and such? Im not familiar with the process there but I cant see the leaders of that country doing anything to protect western intellectual property rights that they dont make a penny/yuan on. Im sure its like this in any country where the govt has no stake losing revenue due to copyright infringement.

I don't know if they have people doing microstock in China, but they certainly use microstock in China. 

My stepdad works in the nuclear power industry and has lived and worked in Shanghai for the past two years.  Imagine his surprise when during a meeting, the powerpoint presentation had a picture of his son-in-law (my hubby)!