These drones might be useful for some EW/Cyber warfare and maybe as advanced counter measures but assassinations? pffttt the US and many other countries have[0] loitering munitions that could be much more effective at those tasks than a drone that wont survive a collision with a house fly from the look of it.
The whole swarm thing is also overblown, the USAF is looking into swarm configuration for manned and unmanned aircraft mostly to counter contested airspaces due to the proliferation of advanced AA platforms, the whole idea is to send a swarm of low cost UAV's that could either saturate the airspace and either make the AA tracking systems ineffective or actually use EW or act like anti-radiation platforms them selves and just ram the radar arrays of the enemy missile systems.
The delivery method reported for this particular one is also quite ineffective dumping 100's of those out of the back of a transport aircraft seems to me a much more effective method which also has been tested by the US many time before to deliver loitering munitions mostly Anti-Radiation platforms.
[0]http://www.thinkdefence.co.uk/2013/08/uk-complex-weapons-par... [0]http://defense-update.com/features/du-1-07/armedUAVs_8.htm