Torie you need to read your article.
He uses a mid term election during a tough economic time as his worst case scenario. Parties in power lose midterms all the time. It is the norm. I would not use it to extrapolate presidential elections.
And I don't think anyone on this forum or beyond thinks the Democratic party can jettison white working class voters. That's absurd. Why do you think Dems are so chummy with unions? Only getting 40% of that vote is an electoral drubbing, but even your article states 40% almost ensures a perpetual lock on the White House.
The rich or upper class are by definition a small minority. I don't think anyone in the Democratic coalition would swap all the white working class voters for a handful of latte sippers. Democrats can do math. Obama isn't running the United States like Vermont. Anyone that has paid attention to Obama's track record and been to Vermont wouldn't confuse the two.