One technological advancement that could change the world forever, is to develop technology that could completely replace soldiers in combat. We already have UAVs and robots to disable bombs, so the technology to replace combat soldiers should not be too far off.
Not only should we be able to create machines that could perform the majority of tasks of soldiers, but we should be able to do so while using non-lethal arms.
We should make it our stated goal, just as Kennedy did with the race to the moon, to create the technology to be the first country on the planet to carry out non-lethal combat, both for the lives and well-being of our troops and for the future of peace on the planet.
We may always have conflicts, but if we are inventive enough, perhaps no one ever has to die for them.