Mark Lilla's editorial in the Times this morning is worth a read. He doesn't really take the right to task enough--but that's not his point in this--but he does offer a way to look at the failure of the Democrats. Identity politics cuts both ways, is his basic point, and he makes it well.
For me, the missing piece in the editorial though is the way the right sucker-punched (or rope-a-doped) the Dems into shifting the fight from structural, class-based politics to identity politics, knowing the left would ignore working class and rural, and religious, whites, and thus setting up a cultural struggle where the left simply ignored a huge player for too long. What Lilla doesn't deal with essentially is the way the right has always used culture wars of some sort to divide and conquer. That being said, the only way forward is definitely for the Democrats to figure out how to speak a language that brings the whole country together around common issues.
Culture and identity issues are vitally important, particularly on the personal level, but I do believe it's a hell of a lot easier to get people to live and let live (i.e., not give a fuck who marries who or which toilet you use) if you feel you have a common purpose--like health care, jobs, and a real future for your kids--that you can work towards together.