The Democratic party has shifted. It is now the Sane party. It has no real, sane opposition anymore (see: state-sponsored religion) so it's up to them to fill the void and take ALL sane positions now-- not just liberal positions.
It's brilliant, actually.
The Republicans go off the rails for a few years. Disappear into the realm of certifiable insanity and legitimate rape. When they finally "right the ship," so to speak, and return to actual politics, it's to a completely mutated Democratic Party: polarized, squabbling, dying for compromise, for anything really-- anything resembling sane conversation or realistic ideas.
We're close to resembling this right now. Let's hope Republicans aren't that smart. Or if they are, someone keep that Todd Akin guy in front of a camera as a reminder.