Once the astral body has shattered the parts of the higher consciousness and light of the being that incarnated will go back to the higher dimensions from where they came. The spirit will see clearly once again, remember who and what it is and realize that the life it just lived was but a tiny (but very meaningful) experience on its journey throughout the Universe.
Ka is basically light from the higher dimensions. Above the dimensions of Astral Substance there are many dimensions of light. The light at the highest dimensions has the fastest vibration and is the brightest and as we come down in dimension the light becomes less bright until we reach Astral Substance which is the least bright but much more dense. The main difference between ka and Astral Substance, although they are both essentially light, is that Astral Substance has a density which allows it to crystallize, and crystallized Astral Substance tends to block and distort the light. The ka cannot crystallize like Astral Substance as it is vibrating too fast. Anything in the dimensions of ka is an expression of the consciousness that created it.
We all have Light Bodies which are made of the light from these higher dimensions. While in your light body you are in touch with your true self and most essential nature as it has not been distorted by the lens of the astral body or the physical body. You know who and what you are and are at one with the Universe. You can travel to almost any dimension in your light body.
We all have this Light Body so where is it? It is waiting for you for when you leave your physical body. When you die and your astral body shatters, the consciousness and light that you incarnated during the life will remerge with the rest of your light body. At this point all veils will be gone and you will remember everything. What is important to understand is that there is a Light Body along with many of your higher selves waiting for you after each life and you will remerge with these parts. I say many higher selves because there is more than one level of your Higher Self. While on Earth you could become aware of your Higher Self and even partially incarnate it. You would then realize that there is still another Higher Self than this one and so on.