Throughout his tenure as leader of the Palestinian Authority, Mahmoud Abbas has studiously avoided grooming a successor, instead consolidating his control over numerous Palestinian entities and sidelining officials he perceived as threatening to his rule. When he eventually exits the scene, Abbas will leave many leadership roles to be filled—including in the PLO, Fatah movement, and national security agencies.

The Gulf nation of Oman has been ruled by Sultan Qaboos since 1970, when he overthrew his own father. The seventy-nine-year-old leader has enjoyed wide popularity, but he has a history of illness. To ensure national stability and continued progress, his successor will have to enact far-reaching economic reforms, aimed especially at broadening the economy beyond its current oil dependence. At the same time, a new sultan will need to navigate challenges posed by powerful neighbors such as Iran, the UAE, and Saudi Arabia.

Whether the young Saudi crown prince ultimately ascends to the throne will entail plenty of plot twists, but it also holds serious implications for the kingdom, the region, and U.S. interests.