You already have these areas, in fact the opposite happens. Skid row in LA has been a rough part of town for probably a century. As a result, that's where the vast majority of services are located. On top of that, impovershed people live all over town in CA. Across any arbitrary 500 feet in a CA city you might see one family living in a million dollar+ home, a single family crammed in a tiny apartment, and encampments and RVs spanning the in between. Rich and poor already live on top of each other, this would at least mean the impoverished who are already living in a given neighborhood are housed instead of the status quo which is living in the same neighborhood but in a tarp with no plumbing.