翻译为减少跨越鸿沟的机会，是不是好理解了。

cross：to pass across each other 相交。

句中的them指classes，整个句子还原一下应该是：Economic weakness decrease  opptunities to cross classes。经济疲软减少了阶级之间交叉的机会。

根据意思理解，阶级之间交叉说明【阶级间的差距缩小】，调整语序，句意变成：经济疲软减少【缩小阶级差距】的机会。换成较为书面的表达，就是减少阶级【隔阂弥合】的机会。

divide 是可以“弥合”的(弥合：close; bridge;patch)，例如：

In the end, he ascended Dominion Creek to its head, crossed the divide, and came down on the tributary to the Klondike that was later to be called Hunker Creek. (BBC)

Mr Applegate's performances cross the divide between a niche musical genre and mainstream.