Not really. If you earn $120k a year (just over 6 figures) you're in the top 10% of income earners in the US. The fact that you think they're 'middle class' (and relatively speaking, I don't think you're wrong) is indicative of how bad the wealth gap has gotten.
Source: http://en.wikipedia.org/wiki/American_middle_class#Academic_...
Still, I think your source really just proves my point: by no means is anyone earning 120K a year "solidly middle class". By pretty much all of the definitions you listed, 120K a year would either be "upper middle class", or "the rich" (e.g. find me a homeowner in SF who doesn't have >1 million in home equity).