A modern brigade can now be tracked, targeted, and struck by systems costing a few thousand dollars. The economics of attrition have inverted: defenders trade million-dollar platforms against disposable hardware produced by the thousand.
Armour is not obsolete, but it is conditional. Survival now depends on active protection, electronic warfare, dispersion, and counter-drone fires layered together — a system-of-systems problem rather than a question of thicker plate.