If the book, Heart of Darkness by Joseph Conrad, were written in this day and age, would there be a good setting?
The Congo region was being exploited by imperialist powers in The Heart of Darkness. Today's exploitation happens most often, arguably, in the poor regions of Asia and Africa.
Those modes of exploitation tend to be oriented toward production and human labor, however, and not the exploitation of natural resources. The Middle East might be the region of the planet today that is most often portrayed as being exploited for its natural resources. The cultural differences between the Islamic Middle East and the West are often depicted as being extreme. This cultural difference seems to parallel the contrast between the imperialist West in The Heart of Darkness and the natives of the Congo region.
As you may already know, Conrad's Heart of Darkness was adapted by director Francis Ford Coppola for his 1979 film Apocalypse Now. Instead of Africa, Coppola used the Vietnam War for his background, with most of the movie being set in Cambodia. The name of the main character in Conrad's novel, Charlie Marlow, was changed, but Coppola kept the character of Kurtz in the movie (played by Marlon Brando). If you are looking for an even more modern setting for Heart of Darkness, perhaps the Middle East (Iraq or Afghanistan) would be suitable; and the more recent troubles in Libya would also be a consideration.