This expedition couldn't have been more timely because as the country slowly opens up, its Asian neighbours and developed nations alike are scrambling to establish diplomatic relations, many of whom would ultimately like to take advantage of Burma's natural wealth.

【翻译】这种考察不可能更及时地实行，因为随着该国慢慢开放，亚洲邻国和发达国家都在争相与其建立外交关系，其中许多国家最终还是想利用缅甸的自然财富。

1. 本句中的couldn't have been，表示对过去情况的可能性推测。意为“过去可能没做某事”。详情参考：http://ask.yygrammar.com/q-7164.html

2. whom 指代its Asian neighbours and developed nations。