Simply because as a matter of fact China still has plenty of rural surplus laborers and people are talking about a magnitude of more than 200 million - so you know from national-wide point of view, there is plenty of labor supply there.
There are various hidden uncertainties if we look at the main growth engines. Exports depend on external factors and it will be a big question as to whether China's exports can be a single flower blossoming if the world economy slows next year.