As China's wages increase, there will be more vacancies for undesired works. Also, development will attract illegals. It is better to have strong control and tracking system to hunt down and deport those that stay in China illegally.
Those who come through legal channels are welcome.
Nevertheless, those jobs going to people from China's historical cultural sphere is more reasonable than going to people from totally alien places/cultures.
Let the West enjoy the fruits of multiculturalism in the form of ghettos.