Also see this Integral Options post, where William quotes at length from Integral Psychology on sub-personalities. (The average person has at least 12!) Also see Wm's post on differentiating a 'core self' from one's sub-personalities. One of the methods mentioned for so doing was psychosynthesis. Here's an article on the latter as it relates to sub-personalities and Wilber's work. Note per this that the core self is as follows:
"One of the central assumptions in psychosynthesis is the notion that we are not the body, the emotions the mind or any of the manifold roles we are playing in life. Our true identity is the self – the point of pure self-consciousness and will. We call this self the conscious 'I' when dealing with the ordinary consciousness and the Transpersonal Self when we address higher and universal consciousness. This point of self-consciousness and will acts more or less consciously through the psychological functions and the subpersonalities and in doing so, it is participating in the evolutionary quest for self-realisation in cooperation with all the other beings on the planet."
Also see John Rowan's website. He is Wilber's source quoted above on sub-personalities. In this section on mystical experiences (at the end) he explores the differences between a causal and nondual state.
Also see Chapter 6 of Integral Spirituality on the shadow. Wilber also posits that the true self or I-I can integrate disowned sub-personalities via the 3-2-1 process. For example:
"You have dis-identified with everything and become one with everything, transcending and including the entire Kosmos" (158).
And when one transcends and includes all states and stages (and shadows) up to the present time in history:
"All states and stages are object of your subject, all I’s have become me and mine of the great I-I, the open Emptiness in which Spirit speaks, the nondual suchness of the Godhead of this and every moment, the Supreme Self that owns the Kosmos arising as One Taste" (170).
I guess at this point an integrated state-stage-shadow is no longer a transitional structure? Or maybe the stage aspect, given that evolution goes on, remains transitional, even at the highest level so far, indigo (or translucent)?
See for example the section on the WC lattice in IS. He notes that “there are also 3 or 4 higher structures beyond the centaur, and they have similar-sounding characteristics as these 3 or 4 higher states, which made it almost impossible to spot the differences” (p. 112 in the linked source). Wilber discusses these higher structure-stages at p. 122 using Fowler:
“There are somewhere around 3 or 4 stages of faith beyond his stage 6 (which is roughly a turquoise-level faith), so we would expect to find that, being laid down now only thinly as Kosmic habits but still discernible (although less so the higher up you go in altitude on a mountain that is being co-created by its climbers), some version of indigofaith (at the same altitude as the trans-planetary mind, then violet faith (meta-mind), then ultraviolet faith (overmind)…, as faith itself becomes Fuller and Fuller and Fuller…, grounded in a Freedom and an Emptiness that never changes, that is timeless and eternal, the great Ground and Openness of the entire evolving display, that nonetheless is Witness to its own display evolving” (my emphasis).