Although such a scenario can be canceled by various preceding events (including a massive world war), it may be possible that in a relatively near future (end of 21st century) the core parts of armies will be robotic. Such a development can actually help with other things, given war is the most serious (due to how lethal it is) business: antagonism in programming and counter-programming those virtually all-robotic forces has to advance way past what already exists, and this in turn should mean advancement in the needed systems of knowledge, such as math. I generally like the idea of robotic forces, as long as they won't be primitive (current drones) and so dependent on humans for managing. It will also allow for events like the one in the scifi story I HAVE NO MOUTH AND I MUST SCREAM. Compare with how useless any single individual is at war if we are dealing with something like napoleonic wars or ww2, and how potentially important a single - genius - can be in a fully robotic warfare.