All powerful weapons may be a huge concern, but it is the increasing abilities of robots that have always founded most future technological worries as man becomes outperformed by machine.
We can try to hide from the robots of the future, but we won't be able to outrun them.
US agency DARPA has already developed an imitation cheetah which can reach a top speed of 18 miles per hour on a lab treadmill and are working on the four-legged robot going a lot faster outdoors.