Now that saying is being turned on its head as America undergoes a transformation from a society for youth into a nation in which middle-aged and elderly people set the pace by mere force of number.

【参考答案】

由于美国正经历着从青年化社会向中、老年人仅凭其占优势的人数就可决定社会主流的新局面转变，那句话正在失去影响力。