Writing at The American Interest, Walter Russell Mead suggests that the left may have peaked with the Obama administration. He makes some good points, but I'm not quite as optimistic as he seems to be. For one thing, Obama still has two years left in office with no threat of electoral consequences to prevent him from fully embracing the darker angels of our nature, so I expect things to get much worse still before they start to get better; the GOP won big in the midterms, but if they won't stop Obama from sidestepping Congress whenever he feels like it, then how much of a victory was it, really?
Mead is also much more dismissive of Elizabeth Warren's chances than I am. Yes, she's a leftist kook with a practically nonexistent resume and a partially fabricated bio, but so was Obama; nobody thought anything of Obama either when he ran against presumptive nominee Hillary Clinton in 2008. Mead thinks it was a unique set of circumstances (mainly Iraq and the financial crisis) that propelled Obama to the White House, but that theory doesn't really explain how Obama got reelected in 2012, does it? I still think our problems as a country run much deeper than many of us would like to admit.
(Hat tip to @rdbrewer4 for finding Mead's article.)