Judging by all the photos we've got so far PLUS the new trailer, it realy looks to me as if Sophia bites the dust.

Carol's extreme reactions and uncontrollable sobbing (in some scenes Shane and or Lori are trying to relax her)are the main things which I think give it away. There's also a shot of her running towards something (or 'someone') in hysterics and later on inside of a church talking to a Jesus statue. There's also the zombie popping up next to Sophia and her running alone crying.

What's interesting as well is that, after we see the two of them at the Vatos building and the highway, she's never seen by Carol's side again (which she always has been) let alone SEEN in general!