Alternatives are being sought, even by U.S. allies.

Even by many U.S. citizens, lol.

I think part of why we target Iran so hard is because they are Shia (which itself has many smaller factions) and Saudi is Sunni. Based on your observations on why the U.S. Government and Federal Reserve needs them so much, it would make sense that is a huge reason. There is a lot of strong systems that sprang from the Shia side, like Babism and Bahai. Their claims being the return of the hidden Imam which would mean if correct that all Islamic countries would need to turn over their kingdoms to them (Babism died with the execution of the Bab, Bahaullahs teacher). It can get violent (as earlier Christianity showed between sects, and with non believers) the more extreme positions and notions that are held.