Let me just focus on one issue raised:
[The] real sort of holy grail of technologies that I’m trying to find on this thing is material, is the armor itself…. If we can discover a material that is significantly lighter in weight that gives you the same armor protection, that would be a real significant breakthrough.
Weight has always been a problem for the American Army. Tanks need armor to survive (and for the crews to survive, of course), which adds weight.
But because America has to ship tanks across an ocean (or two) to fight, heavy tanks are a logistics problem.
Which means that a light vehicle (airmobile even!) with the power and protection of a late-model M-1 Abrams is the tank of the Army's dreams.
So light armor would be the solution, right? I don't think so. As I concluded in that Military Review article, the wonder tank will not be built.
Consider what would happen if we developed armor with half the weight that would provide the same level of protection.
First of all, because of the need for all around protection, we'd add more armor to the sides and rear--and especially the top for defense against top-attack rounds. And mines would require thicker armor on the bottom.
And if enemies go to 140mm tank guns, maybe adding some more armor to the front would be a good idea. And more everywhere else, too.
So I wonder if we'd have any weight savings in the end.
But what if it was really a breakthrough and we have armor with a tenth of the weight?
One, I assume enemies will develop this, too. Enemies will still have the advantage of not needing to move their tanks by ship or (God forbid) air to the battlefield (assuming the Navy and Air Force continue to keep enemy armies an ocean away). So enemies will add on even more of this lighter armor rather than just accept the same protection but with lower weight.
So we'll need a bigger gun on our tanks to handle that thicker enemy armor. And the enemy will add bigger guns, too. So we'll need more protection and so will add more armor all around to protect against the bigger enemy weapons.
And if rail guns allow the Army to move beyond the recoil problem of guns bigger than 140mm? Hello, even thicker armor if enemies follow suit.
Well, unless we figure out a way to kill or disable a tank or its crew without putting a hole through all that armor protection. (Would it be possible to fire a round that hits--or even just gets close enough to the target--and generates enough of an EMP or just an electrical surge locally that it would fry the electronics or electrical system of the target? Just a non-engineer thought. That might be a stupid idea, I admit.)
Not that we shouldn't pursue lighter armor. If a continental enemy got it first, our tanks would be in a world of hurt by being heavy yet not protected to the same degree.
My guess is that the weight of the tank and infantry fighting vehicles won't go down by much even with a breakthrough in armor that everyone will eventually deploy.
Unless we go to full robotic tanks that are designed to be expendable, but which we mass produce.