I really feel that the Democratic "divide" is vastly overrated. It's an incredibly united party right now, especially considering the state of the GOP, and their only disagreements are on how far to go or how to proceed with the same fiscally liberal/populist/anti-Wall Street agenda. For example, Obama wants to go less far than Warren. However, it's a unanimous voice coming from the Democrats denouncing deregulation, calling for a minimum wage increase, taking corporate donations out of campaigns, etc.
It seems united, but there has been a growing rift between moderates and the more radical left wing base since OWS.
I forsee a 2000 like situation in 2016, where a green party candidate manages to sweep up votes from dissatisfied democrats from the radicals who feel that the democrats have been too moderate.
Go to left wing blogs and forums and they have became absolutely hateful of moderates, calling them "turd way", centre-right, secret conservatives. And what else.
Ane its getting worse if to consider the idea of the filter bubble, which has created an echo chamber among the left, ans causing moderate democrats like me to drop out from the democratic party all together due to the hostility I and many received for " Not being left enough"
If Warren or sanders even manage to get the democratic nomination, a 2000 like split with the far left might be prevented. But a savy moderate republican could be very instrumental in getting moderate democrats to swing for them in 2016 if a moderate democrat doesn't get the nomination.
Lets not forget that McCain was actually surging on Obama due to Hillary voters in 2008, dropping out. And that only changed and they decided to vote for Obama because of the financial crash in September of 2008 and the subsequent rise in unemployment..
Edit: Also to add, for some reason the fact that Southern democrats and many democrats facing tough re-election are running blue dog campaigns which are centre-left in economic policy but centre-right on social issues like guns, seems to piss off the left wing blogs who think that every democrat should be forced to run a generic progressive/leftwing campaign regardless of local circumstances.