Context
John 8:58 should be read within the flow of its chapter and the larger argument of John.
Common Interpretations
This is also why Jesus can say in John 8:58: "Before Abraham was, I AM." He was not merely aware of Abraham from a distance. He had appeared to him. He had spoken with him. He had eaten with him (Genesis 18). He was there. The Malak Yahweh is a prominent figure through the period of the Judges and into the early monarchy. Then, significantly, He becomes increasingly rare. After the prophetic period He essentially disappears — and there is no Malak Yahweh appearance in the New Testament. The reason is the Incarnation.
Current Position
This site's current position is that John 8:58 is not merely a statement of preexistence in the abstract. In the framework of the Angel-of-the-LORD study, it also confirms that the Son's relationship to Abraham was personal and historical, not distant and theoretical. The verse therefore helps connect the Old Testament appearances to the New Testament person of Jesus Christ. The One who appeared before the Incarnation is the same One now speaking in the Gospel.