I thought the goal was to evevtually build a plane that could be anywhere in the world within an hour. There are many more uses for this, of course. Next generation SR71 Blackbird, fire missiles on enemy vehicle, sink pirate ship, etc.
Improved missiles are now able to shoot down the U2, and maybe get close to the SR-71. That makes these planes a liability now, when over developed territories such as the former USSR.
Both were formerly useful, and have been brought out of retirement, when required for tasks that a satellite could not perform, or was not in position for.
I wouldn't be surprised if the x37 mini-spaceplane was primarily useful as a surveillance platform.
