Okay, let's run down the progress of military technology, shall we?
The club or the heavy rock was replaced by the spear and the sword. It still exists as a policeman's billy club and the rifle butt,or something similar, because it still works.
The rifle replaced the spear and the sword 500 years ago, although bayonettes are still around. The rifle is still here and will still be here in another 500 years, just in a different form, in as much different from the Brown Bess as the M-16 is today. that's because it will still works.
Cannon replaced seige towers, trebuchets and catapults, bt the need to apply massive amounts of firepower or force against a fixed fortification or kill a large number of people with high explosives still exists, and will continue to exist.
The tank replaced the horse, and will continue to do so until someone creates the ultimate anti-tank weapon, which of course, will be carried by a man. In the mean time, tanks still work, as do man-portable AT weapons.
The wooden trireme was replaced by the galleon which was replaced by the iron-clad, which was replaced by the dreadnaught, wich was replaced by the aircraft carrier. That's almost 3,000 years of combat at sea, where no human being could survive or support himself, bit which is still worth fighting over because it allows the movement of goods and materials. In the end, the armed ship, organized into fleets, still works. It will continue to do so until travel over water is no longer necessary.
The airplane is 100 years old and many of it's missions have been taken over by guided missiles, ICBMS, smart bombs, stand-off missiles, and SAMS, but they're still here, aren't they? In fact, they're continuing to evolve until they become invisible and capable of aeronautic maneuvers that would kill the pilot. However, they still require people to fly them, maintain them and run them, and always will, because a machine can never mimic the thought processes or think in the abstract like a human being. The day when AI becomes that powerful, we no longer have a need for human beings,period.
The atomic bomb obviated the need for massive militaries in the old sense (the mobilizing an entire populations), but we still have militaries because other people have them, and those militaris still represent threats that nuclear weapons cannot fend off. A nuclear weapon is not a military weapon, it is a POLITICAL weapon. This will continue into the futre until the human race goes the way of the T-Rex. Why? because it still works, when applied properly.
The purpose of this little jaunt through history is to teach you that even though the menas change, the ultimate nature of warfare has not -- it's still about imposing your will onthe other guy and more often than not, you have to level his society in order to do it. Such a savage notion still requires savage means --- people on the end of a rifle, behind a cannon or dropping bombs.
The flip side of all this savagery is that since war is stilla human endeavor it is still regulated by human emotions and logic. Colin Powell talked Bush I into stopping the first Gulf War because he was saddened and disgusted by what our guys did to retreating Iraqis. A machine is not capable of that. Firthermore, removing people from the scene of carnage by leaving them in a control room somewhere to guide the robots causes them to lose those emotions and logic until it becomes a machine vs machine rather than man vs man, and then you lose all perspective. Might as well destroy all life on the planet if we ever get to that point.
Tehcnology is great, but it should never ever, nor will it ever, remove human beings from the necessity of putting themselves in danger.
Robots and nanites are.
You'll see.
And you'll rue the day you doubted me.
But isn't the whole point to be able to inflict harm with total impunity?
Rue, I say, RUE.