Biblical prophecy is not simply a description of a coming historical event made in advance, shortly to be visible to all. Rather, Isaianic prophecy interprets the effects of God's entrance into human history. It embraces a different dimension of reality, which only in part coheres with empirical history. The eschatological appeal of God's rule involves a vision of divine intervention that indeed enters human history, but is not exhausted by any one moment. The quality of God's salvific presence is not limited to one specific event in time and space, but embraces the whole of God's announced purpose for creation, which moves toward consummation. The nature of correspondence between word and event can only be measured in terms of this ongoing divine plan toward ultimate restoration of God's creation. Prophecy thus speaks of a quality of future event. It is not a clairvoyant projection of the events within the unredeemed experience of human history (362).
Update: See Wilhelm Vischer's take on the issue, which sounds close to Childs.