June 29, 2017 6:38 AM EDT

Mohammed bin Salman, favored son of the Saudi King, has come a very long way in a very short time. His father, who only became King in 2015 at age 81, quickly named him Defense Minister and then deputy crown prince. He was given charge of Vision 2030, the landmark reform project intended to modernize the Saudi economy and, by extension, Saudi society. On June 21 his father named him crown prince, removing the final obstacle in his path toward the throne. He’s likely to become King within a year as the ailing father is expected to abdicate in order to use his remaining time to help the son make a solid start. The scale of generational change is impossible to overstate. Salman is 31 years old. He might reign for 50 years.

As King, Salman will face enormously complex challenges. He must bring the Saudi economy into the 21st century by diversifying it away from a deep dependence on oil exports, particularly given the lasting impact of technological changes that have pushed global oil supplies higher and prices lower. He must build a culture of work among citizens who are used to undemanding public-sector jobs and modernize Saudi attitudes toward women to bring their talents into the workplace.

On foreign policy, Salman must find ways to promote Saudi leadership and defend Saudi interests without wasting huge amounts of money on unwinnable wars and endless proxy conflicts in the region. He must build new ties in Asia to avoid excessive dependence on relations with the U.S., which improved dramatically when Donald Trump replaced Barack Obama but might deteriorate just as quickly with the next U.S. President. He must do all this while maintaining the balance of power over time within a complex royal family that now has many thousands of members. In fact, with so many ambitious cousins to manage, foreign policy may be the least of his problems.

The speed of Salman’s rise caught many by surprise, and some fear it will provoke a palace coup as passed-over rivals–led perhaps by former crown princes Muqrin bin Abdulaziz or Mohammed bin Nayef–move to defend the influence of their branches of the royal family. But it’s hard to imagine such a move while Salman’s father is alive, and unless the King dies in the coming months, he will have time to build more support for his son within the family.

When Salman becomes King, he will have a much smoother start to his reign if oil prices recover enough to provide extra revenue to allow state spending on the projects and subsidies that keep the royals popular. Higher oil prices would also help the government raise more money from the sale of shares in state oil giant Aramco. Salman must also hope that the Saudi war in Yemen and the Saudi-led effort to force change on Qatar succeed, since he’s directly associated with both.

In his short time on the public stage, Salman has already demonstrated clear strengths and weaknesses. His biggest challenge will be in building consensus–within a family, a kingdom and a region that all badly need it. He’s come a long way through sheer force of personality–and the power of his father to sweep aside rivals–but he has yet to demonstrate the flexibility and subtlety needed to win over those who doubt him. Even in Saudi Arabia, a country of about 32 million, power alone is not enough. Like all successful leaders, he’ll have to show that he’s capable of learning from his mistakes.

In a world of fast-moving technological and cultural change, the kingdom’s long-term survival is very much in doubt. Mohammed bin Salman will soon inherit one of the world’s toughest jobs, one in which only an arrogant, ambitious man with an audacious plan is likely to succeed. We won’t have to wait much longer to find out whether this is the man for the job.

This appears in the July 10, 2017 issue of TIME.

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