The idea of a cavalry charge is nonsense. Rarely done, and mostly a relic of cinema. The Polish cavalry actually performed quite well during WW2 despite being tarnished as outdated.
The roles of a "cavalry" unit are reconnaissance/scouting, raiding, pursuit. Whether they're on horseback or mounted in M2/M3s doesn't matter. Today the cavalry role still persists in most large militaries because the fog of war requires it.