I’m most with @elbanditoroso in that the Three Laws aren’t real things. And he’s also right that vampire drones aren’t autonomous.
But to the point of the question, expect reasonably close to autonomous lethal drones on the battlefield within our lifetime. It will happen, and it’s unlikely anyone can stop it because they’ll be the ultimate asymmetric warfare tool.
Most likely, the response will have to be authonomous lethal countermeasures to them. They’re developing laser based countermeasures (already in field testing), and these already have some modes where they’re selecting their own targets and just need a human to click OK to kill it. When clicking OK is too slow, you better believe that will come off.
Whether autonomous lethal systems are a good idea or not…they are likely inevitable.