But Friday's accession of 79-year-old King Salman brings the House of Saud tantalisingly close to the end of the line for the offspring of King Abdulaziz, the country's first modern monarch.

Since the death of Abdulaziz - also known as Ibn Saud - in 1953, five of his sons have sat on the throne. And there are others who might want to put up their hand. In a country in which women don't count, it seems no one bothered to count the old man's daughters, but Abdulaziz reportedly had 45 sons from at least 22 wives.

But the sense of the end of the line for this generation springs from an unprecedented step taken by the late King Abdullah in May 2014, when he anointed his youngest brother, Prince Muqrin - a sprightly 69-year-old - as a deputy heir to Salman. And thus intrigue was born.

The Saudis have a way of doing things their way – and that includes doing them with a convincing outward display of unity. But this transition is different, because with the knowledge that Prince Muqrin is in line to succeed King Salman, the vastly more numerous offspring of those 45 first-generation princes are likely to begin jockeying to position themselves for a tilt at the throne in the coming years.

We can only speculate on the extent to which some of the older brothers might be miffed by Abdullah seemingly bringing the curtain down on his generation by elevating Muqrin. Some princely noses are reportedly out of joint because of questions on the purity of Muqrin's blood – his mother was reportedly a Yemeni concubine who Abdulaziz did not officially marry.

Similarly, we can only speculate on the extent to which the new king might also be miffed at being dictated to from the grave – all his predecessors were allowed to exercise their right to name their successor.

Saudi-watchers will be transfixed. King Salman has a reputation as the family's enforcer but also as a steady conservative hand. But reportedly he suffers dementia and/or Parkinson's disease and may already have suffered a stroke. His age and poor health are expected to lead to a quick succession for Muqrin, at which time it will be on for young and old in the next generation, which teems with would-be kings because a good number of the aforementioned 45 princes produced their own heirs – the late King Saud, second on the modern state's throne, reportedly fathered 53 sons.

Given the repressive character of Saudi society, not a lot is expected to change under King Salman – women still will not be allowed to drive and those who do will be tried in a special terrorism court, nor will they be allowed to venture out of their homes; bloggers will still get the lash; and the Wahhabi clergy will still hold sway over the royal household. And despite royal irritation with - and even a bit of contempt for -  Washington over the conduct of the Iraq War, Iran's nuclear program and the Obama administration's refusal to prop up Egyptian dictator Hosni Mubarak, the Saudi security and military establishments will continue to work with their US counterparts, if only because of their deep-seated fears of the so-called Islamic State and of Iran's regional ambitions.

At great financial cost, Riyadh fended off the social challenge of the "Arab Spring". But the country sits on a security hair-trigger these days – choking dissent and fretting about the intentions of its restive Shiite minority. And even as Riyadh continues to work with Washington in the security sphere, it will probably continue to work against the US on oil prices – a Saudi refusal to go along with pleas within OPEC for cuts in oil production to put a floor under prices, which are in free-fall, is seen as Saudi punishment for Moscow and Tehran, both of which are desperate to increase their oil revenues.

But as it watches prices tumble, Riyadh is also poking Washington in the eye – with North America now on the verge of energy self-sufficiency, this Saudi gambit has left US oil producers paying more per barrel in production costs than the price at which they can sell.

Bruce Riedel, a CIA veteran and former White House adviser now at the Brookings Institution, looked ahead when answering a reporter's 'what next?' question: "If and when Muqrin ascends to the position of crown prince, the kingdom will face the unprecedented challenge in picking the next in line from the grandsons of Ibn Saud – that will raise questions of legitimacy not faced in the last century of Saudi rule."