I'd say that is nowadays almost completely just a direct consequence of general population decline, and not some more specific effect; this just hits rural communities harder because attracting new people is already difficult there (=> most job opportunities are elsewhere), and it is much easier to fall below "viability thresholds" (i.e. too small to sustain a general store) than it is for cities.

I'd argue that the "real" urbanization mostly finished in the 1980s or so, and the "urbanization" we see now is mostly incidental (and happens at lower rates, too).