I’m fairly certain as to why the Saudi deputy crown prince has been removed from succession. Two weeks before ISIS/Daesh struck Iran, the prince said that the war should be brought within Iran’s borders. Now after ISIS attacked Iran, it has become far more involved in the Syrian conflict. Just a few days ago they launched a missile attack on a terrorist stronghold causing a good deal of damage to their forces. It seems that the crown prince has harmed the Saudi effort in Syria by giving Iran a reason to get more involved in the conflict. This has angered King Salman bin Abdulaziz Al Saud, causing him to remove the crown prince.
Original story: http://presstv.com/Detail/2017/06/21/525997/Saudi-Arabia/