The use of lighting is important in the series. The first three episodes depicted light as the glimmer of hope. The light coming through the windows of the addict's church building in the very first scene, the lamps of the Clark household on the first night, the flicker of life in the eyes of the living. Wherever the source of light emanates from, there is life, and there is still hope.
The blue glaze over the eyes of the walkers no longer projects the glow of life within. As the "walkers" depict the pretense of life, so the world, the city, the neighborhood has become the pretense of civilization. Who will continue pretending?
Now, the electricity is fading, and the flashes of light seen from Chris's rooftop perch are not survivors seeking help, but muzzle flashes of warning. Everything has truly changed. The survivors, I predict, will be the ones who stop pretending that everything's still normal. Who will make the change before they also "turn"?
Side note: We are spellbound by the series Fear the Walking Dead but oblivious to the plight of hundreds of thousands of refugees pouring out of Syria into an overwhelmed European community. The irony is not lost here. When will Americans stop pretending it's okay as long as it's someone else's problem? That, in fact, it's everyone's problem in a globally connected world.