Here in NJ single-family homes are sitting on the market because of the drop in birthrate; unless a homeowner can convert it to a 2-family there is too much space for a couple with either a child or a pet (and the taxes are prohibitive). Many towns turn a blind eye to such modifications, and when they are alerted they tend to allow the 2 family to remain (with increased taxes, of course).
While I see the trend against single family homes continuing, I see demographics rather than (though maybe due to) government policy driving it.
Government policy is that unborn babies SHOULD BE destroyed, and that they SHOULD NOT be conceived in the first place. The left does not just fanatically support abortion, it also fanatically supports contraception and faggotry. All of these things are an attempt to engineer population decline. Leftist death lovers are literally trying to destroy American civilization.