It has been doing this for decades already. North up the coast. Across the wastes of Phoenix which built outward into the desert, and also to Texas which I hear has similar sprawl.
So we have established that housing and homelessness need to be solved at the national level. As such, the influx of people to California to begin with stemmed from within California along with other parts of the country—it has always been a national issue but only visible at the local level.