Postmodernism, as a literary style,focuses on self-awareness, irony, and deconstruction of typical ideas. Here, King's statement that he has a "dream" highlights the fictionality of his "dream," that's to say he recognizes - overtly - that his vision is a "dream" and, hence, not connected directly to reality. Like any great Postmodern author and thinker, he is offering commentary upon an overtly "fictional" vision of the future.
