Surely it would only be a matter of choosing to increase the efforts for a year or so in order to take these weapons from proof-of-concept to highly effective. E.g. autonomous flying gun platforms that can be deployed en masse and let loose with small or no human oversight (e.g. "hold the button to kill the person the machine has identified as a valid target", if even that level of control), or the kind of flying, target-seeking grenades envisioned in the linked video. With any level of autonomy, loitering and communication with command. It's only ethics and public perception that stops this today. In total war, a 20% mis-classification rate doesn't matter. Bombing doctrine in WW2 was much, much worse than this in its effect on civilians. Hell, many military leaders emphasized killing civilians as a desirable objective. Even present-day attacks consider "collateral damage" acceptable, even if politicians sometimes pretend otherwise.
Defending against weapons like that would be an arms race in itself, and completely beyond the reach of weaker actors. At least on a tactical level. Maybe there's strategies that could be employed as a low-cost defense, such as staying out of sensor range or confusing the sensors with adversarial patterns, but it would crush the resistance of anyone that tried a conventional defense.
Does the post-WW2 doctrine of emphasizing trade and the un-profitability of war, or ensuring that it is more economical for everyone to support a stable, free democratic economic system, still have any hope of preventing such weapons from being used?
