The threat isn't the addition of guns, it's the removal of conscience, reason, and consequence. Bioweapons, nukes, whatever - they require a person to address their own conscience before utilizing them. Killdogs just address their programming.
I think there will still be a human who deploys a killer robot, until AGI that is.... Also I don't think someone deploying land mines is thinking about the consequences beyond the immediate conflict, and they will kill/maim years after.
We are moving into the Afghanistan 'we don't know who's an insurgent so drone bomb anyone holding a radio' stage of warfare and humans are not ready for the ease and lack of accountability that comes with it.
