Technology is changing at an astonishing pace. By the end of the American Civil War wooden hull ships were obsolete, along with muzzle loading guns and cannons. Everyone thought the first world war would be a war of movement and the cavalry would be king. Barbed wire ended that. Along came the airplane and nations were still preparing for war by building battleships. In the next war battleships barely took part when compared to aircraft carriers. We are constantly upgrading and improving the weapons that were important during the last war. The danger here is the enemy has all the time he wants to study what you have done and come up with a counter.
With the advent of fully robotic manufacturing, miniaturization and the inevitability of Moore’s law, I suspect the next war will see clouds of robotically produced drones ranging in size from a small fighter plane down to a seagull. I think we are entering the age of swarm attacks. Unfortunately, the military industrial complex is tuned to produce big, expensive weapons, primarily because that’s where the money is. Politically, Congress isn’t interested in small weapons built by robots because robots don’t vote.
I am in favor of giving the guy on the ground the best weapons and best protection we can afford. However, history shows that Donald Rumsfeld was right; “You don’t go to war with the weapons you want, you go to war with the weapons you have.” I hope somewhere, perhaps in DARPA, somebody is developing and planning to rapidly field the weapons we will want.
Actually, only the Europeans thought that WW1 would be a war of movement. There were a number of Americans that figured it would look more like the end of the Civil War where it had actually begun devolving into trench warfare.