Doing research for this answer about interplanetary cubesats, I watched the NASA Jet Propulsion Laboratory YouTube channel video CubeSats (live public talk) of a talk by Dr. Andrew Klesh, Chief Engineer for Interplanetary Small Spacecraft, JPL.
At one point in this really interesting and informative video, when talking about the Interplanetary Nano-Spacecraft Pathfinder in Relevant Environment (INSPIRE) (See also eoPortal), the speaker says:
So these spacecraft are ready for flight and are sitting on the shelf now. In fact they had a launch opportunity along the way, but in fact something else stole it, and that was an unfortunate day.
What stole the launch opportunity, and are there any current plans for another?
Video, queued at