The US government created NASA to focus American efforts toward a single goal: put a man on the moon in a non-military context (albeit with mostly military flight crew and inherently military overtones in the goal itself). Having accomplished that mission, NASA has remained at the center of almost all US space efforts, except for those with military objectives.
With all the various interests in space from commercial, institutional, military, and private entities towards a variety of objectives including exploration, research, resource development, and even tourism, does the US government still want to keep NASA central to it all, or is there an alternative vision? I once read something which declared an aim to get NASA "out of the space launch business", but it still appears to be heavily involved in the development and construction of space hardware and the ongoing business of launching payloads into space.
Consider aviation... there is the FAA and the American air traffic control system which exists to promote aviation and to promote increased safety in aviation. It doesn't transport people or goods, build aircraft, or do aeronautical research, generally doesn't operate aircraft at all, leaving that to private, institutional, and commercial operators.
Is there a similar model in the works for America in space?