Here is a WSJ article on the implications of the shake-up. Lots of interesting comments about the future economic implications of our changing relationship with Iran and Saudis.
http://www.wsj.com/articles/new-saudi-king-brings-major-change-at-home-and-abroad-1430310152
What is the gist of the article?
> “The Saudi Arabia we knew a few hours ago is no longer,” Jahshan told Al Jazeera...
Since the death of Saudi Arabia’s founder, rule has been passed down through his descendants via just one of his wives. Obviously his children are all geriatric (or already dead), so this move was inevitable. Better to do it in a planned fashion than during a crisis of succession.
Probably the recent bombast by the Iranians that the Kingdom is doomed comes from that system of succession.