Ibn Saud clearly regarded Muqrin as a full son. The question now is the attitude of Muqrin's sixteen half-brothers and his many nephews, who might regard their own pedigrees as superior. Apart from age, the other criteria for becoming king are experience, acumen, popularity, mental stability, and the status of one's maternal uncles (which indicates whether one's mother was a slave or concubine).
CURRENT ROYAL FACTIONS
Muqrin himself has no recorded full brothers, a status he shares with King Abdullah, which might explain the perceived bond between the two men. Fraternal alliances have been significant in royal politics. For decades, the so-called "Sudairi Seven" -- full brothers Fahd, Sultan, Abdulrahman, Nayef, Turki, Salman, and Ahmed, all born to Hassa al-Sudairi -- were a crucial constituency. Although the deaths of King Fahd and Crown Princes Sultan and Nayef depleted the bloc's strength, Crown Prince Salman continues to lead the faction despite his dementia, propped up by his own sons and Sudairi nephews.
Assessing the combined strength of these nephews presents its own challenges. Muhammad's elder brother Saud bin Nayef was recently named governor of the oil-rich Eastern Province, but he replaced another Sudairi nephew, Muhammad bin Fahd. In addition, one of Salman's sons has been appointed governor of Medina province. Clearly, the Sudairi nephews possess the experience and ability to remain a significant force in palace politics.
LEGAL AMBIGUITY
Saudi laws and official statements fail to clarify how the current situation will evolve. The 1992 Basic Law of Governance (http://www.saudiembassy.net/about/country-information/laws/The_Basic_Law_Of_Governance.aspx) merely states that "rule passes to the sons of the founding king and to their children's children." The principal qualification is to be "the most upright among them," and this vague criterion is not defined.
In 2006, King Abdullah established an Allegiance Council of princes to help guide future succession. Yet the scope of its role is ambiguous: the council was not involved in the selection of new crown princes to succeed Sultan (who died in 2011) or Nayef (who died last year). In both cases, Abdullah chose the replacement and the council merely approved it. The Allegiance Council Law does include a mechanism to replace the king and crown prince if they are incapable of carrying out their duties for health reasons; the kingdom is arguably nearing this point.
Legally, Muqrin's new post -- second deputy prime minister -- exists only to provide an additional person to chair the weekly Council of Ministers meetings; the position has therefore gone vacant at times. According to the Law of the Council of Ministers, these meetings "are presided over by the king, who is the prime minister, or by a deputy of the prime minister." It is therefore by convention, not law, that the second deputy prime minister is destined to be crown prince.
Whether any of the above legal documents or bodies will actually be used to determine Saudi Arabia's future kings or crown princes is a matter of conjecture. There is nothing to stop the king from abolishing the Allegiance Council and establishing alternative procedures. Meanwhile, various succession scenarios are swirling through the kingdom and the wider Arab world. One is that Muqrin will become king and appoint Abdullah's son Mitab as his crown prince, thereby cutting out Sudairi challengers. Although rivalries within the House of Saud traditionally play out behind palace walls, the increasingly high stakes suggest that the rest of the world may get a glimpse of the coming maneuvers.
