供參考：
你改成"That will mean social advancement will remain a distant dream for growing numbers of people" 與原意一致，但是原文更強調(diào) “growing numbers ”一些。另外你覺得缺的（即原文省略的）可以是“people”， 也可以是 “disadvantaged", "retirees", "colored", "immigrants", 等等，這要看上下文才知道。

In China meritocratic exams（精英考試） have been revered since imperial times（封建王朝）, when any man could sit them to enter the civil service(仕途). For centuries they enabled the poor but talented to rise to high office. The gaokao is similarly intended to be a great leveller. But society has become increasingly divided between those with degrees and those who never even went to senior high. That will mean growing numbers for whom social advancement will remain a distant dream.

作者：頭條號 / 翻吧
鏈接：https://toutiao.com/i6293708732874359298/
mean sth +從句=mean +從句 for sth ，

理解正確，你的改寫從意思上看也沒問題；區(qū)別在于原文更突出強調(diào)“growing number”，而你改寫后比較平鋪直敘。growing numbers 就象你的改寫, 指 “growing numbers of man/people", 但有了上下文，不加這個”of man/people" 限定也不影響，句子顯得更精煉些。

個人認(rèn)為，growing numbers后并未省略什么，它在此的意思是＂不斷增加的人數(shù)＂；后面的for whom是介詞賓語從句，用來修飾這個numbers作定語。
感覺句子結(jié)構(gòu)最好不要改，否則有頭重腳輕的味道。