Hard for my mind to process this is...
By the end of the 4th episode almost all of the cabin group is gone...
First it was Pete then Alvin (determinant), Nick (determinant), Carlos, Sarah, Rebecca and maybe Luke. I understand that this is the Walking Dead and most characters die. We all felt the same way when the motel inn group was nearly wiped out. It's just that in episode 2 it felt like Clementine was with a strong presence that is going to watch her back for the rest of the season. And now that presence is gone. The cabin group might of not been perfect for Clementine but at least they were more politically stable than the motel inn group. They also had a strong value system which is to not live like Carver's group. So in a way their values were different than the motel inn group. To the cabin group living a secure life while losing their humanity was not enough. They had a dream to live like normal human beings instead of living like animals. That is probably why their leader Carlos had sheltered Sarah because he had a dream of her living a normal life. Since Sarah is gone that dream has died like a fly.
If Luke survives the firefight with the Russians then he would have a important role in the coming plot. Since he's theoretically the sole survivor of the original cabin group he is now a ghost of a dead dream