Nope. Not interested. Doing so would fundamentally change the dynamics, culture, and demographic make up of the country that's been able to withstand many millenia.
China must copy elements in other parts of the world that works and discard things that clearly don't or destructive if applied in China.
The U.S. Canada, Australia and other artificially created modern countries could experiment with mass immigration not entirely done from moral reasons but purely on capitalism and outward expansion when it comes to the U.S. absorbing mostly European immigrants to subdue/genocide the beast a.k.a. Native Americans from their own lands. The same applied to Canada, New Zealand, Australia.
The immigration issue has been the fulcrum of conflict in Europe and why leaders of Hungary, Poland, Austria, Sweden, Denmark, Norway etc...are increasingly becoming anti-immigration because the makeup and culture of their countries are being changed from within. The make up of those countries in 100 years time would not look any more differently than their North American counterparts with their culture essentially being colonized, cannibalized by liberal humanists who are nothing more than nihilistic hedonists which is pretty much the ultimate goals and project by the Liberals.
They essentially want a future with no borders, no discerning culture and where collectivism is all but extinguished replaced by INDIVIDUALISTS who are free to pursue every hedonistic desires.
As PM Justin Trudeau pointed out in the glowing profile penned by the NYT in 2015 stated:
Trudeau’s most radical argument is that Canada is becoming a new kind of state, defined not by its European history but by the multiplicity of its identities from all over the world. His embrace of a pan-cultural heritage makes him an avatar of his father’s vision. ‘‘There is no core identity, no mainstream in Canada,’’ he claimed. ‘‘There are shared values — openness, respect, compassion, willingness to work hard, to be there for each other, to search for equality and justice. Those qualities are what make us the first postnational state.’’
I don't mean to provide a long winded response to your point about China having an immigration policy that can attract peoples of different ethnic backgrounds that in my opinion laudable, humane, and noble but IMHO not suitable for China as of right now.