The Saudi dynasty is facing its biggest dynastic challenge in 50 years, and Game of Thrones-style cracks are showing in the imminent transition from King Abdullah’s rule.

Abdullah, 90, is currently battling pneumonia and temporarily needed help from a breathing tube last week.

The king assumed the throne in 2005 as the country's sixth king. His immediate successor, Crown Prince Salman, is 79 and also reportedly in poor health. Abdullah named his youngest brother, Muqrin, as the deputy heir last March.

The choice of Muqrin, a British-educated fighter pilot who has close ties to the U.S., is controversial partly because he is the son of a Yemeni concubine who was never formally married to his father, King Abdulaziz Al-Saud, who founded the Saudi state in 1932.

“He is not a real prince; his mother was a slave and there are other brothers who are more competent,” a former Saudi official told Liz Sly of the Washington Post last year. “Nobody believes Muqrin can become king.”

The newly-created title effectively allows Muqrin, 69, to bypass at least two other brothers, which goes against the unspoken rule that succession passes down according to age.

Over the last six decades, the succession mostly passed brother to brother in order of their age. But the last of the current line of brothers will die soon, passing power to the third generation of the family.

Saudi Arabia's Crown Prince Salman bin Abdul Aziz al-Saud waves upon his arrival at the airport in New Delhi February 26, 2014. Salman is on a three-day visit to India. REUTERS/Adnan Abidi "Placing Crown Prince Salman and Prince Muqrin in line to succeed Abdullah effectively delays the time of reckoning when the next generation of princes, the founder’s grandsons, will be moved into positions of high authority," Rick Gladstone of The New York Times notes.

Sly explained the problem that consequently arises when the next generation takes over:

"Given that there are scores of princes in [the third generation], the potential for discord is high. Whoever inherits the throne is likely to anoint his own brothers as future heirs, thereby cutting out multiple cousins from access to the throne and the patronage it provides."

The conservative kingdom has recently refused to cut oil production to stop prices from falling further, preferring to let the market run its course. That policy could change at any time, such as a situation in which the royal family wants to stir public support during a succession.

"A power vacuum in Riyadh following the death or extended hospitalization of the Saudi monarch will prompt concern in international capitals because of Saudi Arabia's importance as the world's largest oil exporter. Despite its dominant market position, the kingdom has seemed powerless to stop the recent price fall, instead trying to preserve market share and perhaps undermine U.S. shale exploration," Simon Henderson of The Washington Institute writes. "Other areas of concern would include the impact on the Saudi leadership's position in Arab and Muslim-majority states, particularly in coping with the threat of the Islamic State of Iraq and al-Sham (ISIS), against which Riyadh is a key member of the U.S.-led coalition. Also, simmering trouble among Iran-influenced Saudi Shiite activists is a perpetual worry.

This chart from The Washington Institute lays out the line of succession up to this point (Muqrin is one of the "19 other surviving sons":