Excellent point. The A-10 has to date shown amazing survivability even when hit with multiple types of munitions when coming in low over a combat zone. Yet few of the people it has attacked have been armed with modern SAMs. It might be said that the days of fixed wing aircraft and helicopters over a modern battlefield against a technologically sophisticated opponent are over. As are perhaps the role of naval surface combatants. Warfare is always changing. It was once hoped the modern machine gun would make war so costly that war itself would not be an option. Today surveillance, drones and unmanned aircraft of many sorts are now paramount. Pity the poor ground soldiers who must actually fight and try to survive. No doubt war colleges will adapt what they learn from this war to develop new tactics. The thing that will remain unchanged will be the dying and maiming of the common ground soldier.
The ability to deny the enemy or they us the operational use of air or sea means down and dirty ground fights. Now an enemy can ATGM to effectively deny armor also. Turns into a slugfest. Might as well be a knife fight.