What stole the INSPIRE cubesat launch opportunity, and will there be another?

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 25:40

INSPIRE was officially announced in 2013 as a part of ELaNa round 4. It seems to have been different then the others, because it was waiting for an interplanetary mission that could accept a cubesat. The timeline would have had to have been between 2016-2018, based on the ELaNa announcement as well as the INSIGHT website you linked. We also know INSIGHT is 2 3U cubesats. Possible candidates include:

• Mars INSIGHT- The 2016 launch date.
• OSIRIS-REx- Launched in 2016
• Mars INSIGHT- The 2018 launch date.
• Falcon Heavy/ Starman- 2018.

That's it, those are the only US based interplanetary launches from 2016-2018 that were planned in 2013, so far as I can find. I really doubt anything was ever planned for the Falcon Heavy mission, so my guess is that it was originally intended to launch on the 2016 Mars INSIGHT mission, and when the mission was delayed the decision to replace the INSPIRE cubesats with the MarsCO cubesats was made. It seems they were based at least partially on INSPIRE, but were increased in size and purpose to improve functionality.

Personally, I doubt that INSPIRE will be flown unless the MarsCO cubesats prove to be a complete failure, as INSPIRE was intended as a technology demonstration, but it's hard to really know for sure.

• The presenter chooses his words carefully, so to "...but in fact something else stole it..." the something else would then be Mars Cube One (MarCO), the spacecraft he starts discussing in the following sentence? – uhoh Apr 30 '18 at 0:24
• He talks about InSight next, not MarCO. MarCO comes up later, but... I know it's a bit of a stretch, but... I'll see if I can come up with something more detailed. – PearsonArtPhoto Apr 30 '18 at 0:40
• InSignt is mentioned only because of it's role in the MarCO cubesat mission. – uhoh Apr 30 '18 at 0:57
• Any further thoughts on What stole the INSPIRE cubesat launch opportunity? The words "...but in fact something else stole it, and that was an unfortunate day." sound so ominous and specific. – uhoh May 3 '18 at 8:20