Nothing. Unfortunately, it's alive and well. The Church hasn't abandoned the idea we commit personal sins. "Social sin" and "structural sin" are legitimate terms, but shouldn't be interpreted as negating personal accountability.
In his encyclical on social justice, Sollicitudo Rei Socialis, Pope John Paul II says "social sin" or "structural sin" proceeds from the accumulation of personal sins. It is, says the Pope, "a question of a moral evil, the fruit of many sins which lead to 'structures of sin.'"
Since the source of "social sin" or "structural sin" is personal sin, the solution to it rests with our personal actions. We must do more than change "the system," as important as that may be. We must change ourselves.