A USB controller to make drones into independent robots when flying missions.

It should be possible with the SDKs available to create a USB device that would plug into the drone that would allow it to fly pre-loaded missions at pre-determined times independent of the handheld controller. For ranchers that want to keep an eye on their fence lines, for security runs for plants and neighborhood watches, for monitoring mining operations, etc. Has anyone done this? Is it feasible?

There are bound to be military drones that launch when triggered by perimeter motion sensors and such, but that level of automation would cost a lot more than most civilians would be willing to pay.

Also, having a drone on constant standby ready to launch would require periodic battery swaps due to the auto-discharge protective features of most hobby-grade drone smart batteries. That said, technology marches relentlessly on, and more versatile drones are bound to emerge in the coming years.