Carol is definitely alive. You don't kill off a long-time character with no show/story.
This is NOT going to be a popular choice, but I think Carol may save Lori.
I think all that practicing the c-section on the zombie has to tie back in some way. Maybe Carl didn't have the balls to shoot her. And on the extended preview for next week, Rick runs into the boiler room and Maggie goes "She should have been RIGHT HERE!"
So either Carol manages somehow to save Lori (Don't look at me for explanations, I am just the idea girl...) or Lori and Carol are both zombified and Rick has to shoot them both in the head, driving him even further over the edge of the cliffs of insanity. He is gonna have to be in a very fucked up and dark place to go mano a mano with the Governor.
Can't you just see a half naked Lori zombie with an umbilical cord dragging behind her...