Unfortunately you forget that both KSA and Israel have been on the same page until just recently. Both were somehow put in power by the Brits along with Pahlavis of Iran and Kemal Pasha of Turkey.
You forget, ISIS was a co-production of KSA, Israel, NATO and Arab states with Wahabi ideology.
When the kingdom denied any connection to Wahabism, the movement officially died.
But without Iranian fight against ISIS in the beginning, they could turn into the best excuse for Americans stay in the region for an other century to come.
USA creates cancers and uses them to spread tumor in the body of civilizations. ISIS was the very case to pollute Muslim world.
ISIS has zero to do with Sunni masses.