As would, I’d think, San Francisco under a similar system.
It’s not a good solution. But for the preferences San Francisco’s residents seem to be expressing, it’s the only way. (Fortunately, it’s probably unconstitutional.)
Open immigration for rest of the country from around the world but closed for their city from rest of the country is what these “progressives” seem to want by their actions.
...how?
Anyone in China is free to move to Beijing, rent an apartment, and take a job there. (And they do!) There are zero controls on movement, residency, or employment. The hukou system would prevent immigrants to San Francisco from sending their children to public school or going on the welfare rolls. Are those things they're doing a lot of now?
Yes? I'd say at least a plurality of people who relocate to SF are doing one or the other eventually. The only ones who aren't, are the DINK set who decide to stay childfree.