The Witness is a huge step forward, and it is a necessary and important step in meditation, but it is not ultimate. When the Witness or the soul is finally undone, then the Witness dissolves into everything that is witnessed. The subject/object duality collapses and there is only pure nondual awareness, which is very simple, very obvious.

Grace and Grit: Spirituality and Healing in the Life and Death of Treya Killam Wilber (ed. Shambhala Publications, 2001) - ISBN: 9780834822320