Thanks!
I feel Wilber got stuck on his four quadrants model, and stopped developing his ideas further. There are so many things he had great insights on but never followed up with.
Postmodernity tries to fix many of the problems of Modernity. Modernity fragments knowledge and the world into objective models. Postmodernity fixes this problem by creating more relational models based on social interactions. The other problem Postmodernity tries to solve is the amoralness of Modernity. This is by overlaying a social value system over all knowledge. Knowledge isn't just true or not, but now must also be socially good (equitable).
The next phase I think is 'Interobjective Ecologies' where the hyperreal overlays over the real until it is impossible to distinguish between the two. See here: https://medium.com/p/45d0a29cf9e
Objective knowledge and social myth blend together until we return to a mythical mindset very similar to 'Traditional' knowledge. So yes, full circle, or in Wilber's language a spiraling upward.