One important fracture line to keep an eye on, is the one between Jewish Democrats and the anti-Semitic Left. Jewish Democrats have yet to fully see the face of the beast they have hitched their cart to. When they can no longer avoid look at it, the split will be impressive. Read David Horowitz's "Radical Son", for the story of his awakening and split with the radical Left.
Horowitz is definitely a man I listen to when it comes to this stuff. He grew up in that camp and knows them well.