Looking frail, Oman's Sultan Qaboos appeared on television last month to reassure his people about his health. But after a long absence abroad for medical treatment, many Omanis are worried that their childless leader has no publicly designated heir.
In a turbulent Middle East, Oman remains an island of stability along with Gulf Arab neighbours, and many Omanis believe the succession process could be handled smoothly when the sultan finally departs.
But some fear that any uncertainty could lead to jostling between potential heirs of Qaboos who, despite gradual reforms during his 44-year reign, remains an absolute ruler.
Western-backed Qaboos, 74, has ruled the Arabian peninsula state since he took over in a bloodless coup with the help of Oman's former colonial power, Britain. Since then, he has helped to transform an impoverished backwater riven by internal conflicts into a prosperous state that plays a small but important role in international diplomacy.
It was in Oman, for example, that Iranian and U.S. diplomats held secret contacts which led to an interim deal in 2013 on a nuclear dispute which has long heightened regional tensions.
But analysts fear that any power struggle after the sultan's death within his Al-Said family - or between the royal family and army leaders - could rattle the country. This in turn risks rekindling "Arab Spring" protests that the authorities managed to contain in 2011.
Marc Valeri, an Oman expert at Britain's University of Exeter, believes Qaboos should follow the example of Jordan's King Hussein. The monarch prevented what he feared might be a succession crisis by publicly naming his son Abdullah as his heir two weeks before he died in 1999.
"I think it is very important that he decides who will succeed him, like King Hussein did," said Valeri. "If Qaboos does not designate a successor himself, it will be more difficult to ensure that disagreements among the family remain contained."
Any threat to Oman's stability could have unwelcome implications for the global oil trade - 40 percent of sea-borne crude exports are shipped through the Strait of Hormuz separating the sultanate from Iran - and for relations between Tehran and the West.
Apart from brief statements to reassure Omanis about the sultan's health, the royal court has given no details of his condition or the treatment that he has undergone in Germany since July.
In his video message aired on Nov. 5, Qaboos said he would not attend celebrations marking his birthday, Oman's national day and an event that he is not known to have missed since ousting his father in 1970. He gave no details of his condition beyond referring to "good results that will require a follow-up in accordance with the medical programme".
Since then Qaboos has been shown only once, meeting members of the royal family.
Under Omani law, a royal family council must decide on a successor within three days of the sultan's death. If it fails to do this, a defence council that includes top army officers, the head of the Supreme Court and the heads of the two chambers of Oman's consultative council must enforce the sultan's own choice, which had been secretly recorded in a sealed envelope.
However, the royal family council's make-up is not known publicly and there appears to be no pre-eminent elder who can act as peacemaker in the event of a dispute, analysts say.
"This process raises some questions; the royal family council is unknown to the public and there is a three-day vacuum of power. Who will be in charge during this period?," said Omani academic and political analyst Abdullah Mohammed Al Ghailani.
"Failing to determine the next sultan will certainly undermine the future political significance of the royal family," he added, warning this would also risk politicising the army.
During the Arab Spring, Omanis staged protests in the capital Muscat and other cities to demand jobs, an end to corruption and greater powers for the elected Shura Council.
Gulf Arab neighbours - the world's top oil exporter Saudi Arabia, the United Arab Emirates, Qatar and Kuwait - rushed to shore up Oman's finances and stabilise the country.
Qaboos sacked unpopular ministers, prosecuted some officials for corruption and promised to create 50,000 new jobs, but the demonstrations showed that absolute authority is no longer acceptable to Omanis, Valeri said.
Analysts say Omanis have set a high bar for any new leader.
"What Omanis are looking for in any new sultan is a young person who can act as a father-figure, who will not only earn respect but can also address the needs of the people," said Ahmed al-Mukhaini, an independent analyst and former assistant secretary-general and senior policy adviser at Oman's consultative Shura council.
Progress towards the institutional state has been slow. Qaboos introduced universal suffrage for elections to the Shura Council, one of the two chambers created under Oman's 1996 Basic Law, but it remains subordinate to the sultan.
Analysts say that while there is wide support for the ruling family, the lack of a representative democracy makes Oman vulnerable to the uncertainty that could come with any succession process.
"There have been increasing demands for genuine political reforms including genuine participation, a powerful parliament, freedom of assembly, ... freedom of expression, transparency, accountability, and anti-corruption measures," Ghailani said.