Many Serbs are out of work as we speak thanks to privatization and China did not buy much in Serbia...westerners and Russians did. There is not much of the Made in China staff in Serbia  as opposed to for example Australia where everything you touch is made in China...and Australia is not doing bad nowadays.
Labor is still cheep in Serbia...I have seen last summer that actually western products (very expensive) are everywhere in shops...not much of the domestic. Even if they import "made in China" it will only make Serbian lives easier cause that's going to be much cheaper.
Serbs do not produce very much today...excluding agriculture...unfortunately...or maybe not.
As of what we know is that China will give cheap loan to Serbia and mostly for infrastructure...