From its inception as a technology, virtual reality has promised to revolutionize the way we interact with our computers and each other. So far, the reality of virtual reality has not lived up to the hype. This paper explores what the state of virtual reality interface technology will be in the future by analyzing the current state of the art, forecasting trends in areas relevant to virtual reality interface research and development, and highlighting the barriers to providing virtual reality environments that are immersive and interactively indistinguishable from reality (strong VR). This research shows that the evolutionary pathway of virtual reality technology development will not be able to overcome all of the barriers and limitations inherent in the current generation of interfaces. I use a reverse tree methodology to explore alternate pathways to achieve strong VR. Brain-machine interfaces (invasive and non-invasive) represent the most likely pathway that will lead to a strong VR interface. The US Air Force should continue to develop common VR interface technology using widely available interfaces, but should increase its funding and support for technologies that will enable enhanced brain-machine interfaces to ensure its dominance in training and simulation for the future.