My opinion is: your analysis is totally wrong. The Americans will never be in good terms with Iran because Iran is a threat to Israel, first.

Second, The Americans will not let down the Saudis because we need them for the Petrodollar. Otherwise, we need them to keep the dollar an the international currency. Just imagine if the Saudis get pissed off and decide to sell their oil with Euros Our dollar will crush!

Third. As long as the Saudis- and few other artificial countries in that area- are not a threat to Israel and enemies of Iran, we will keep buying their oil to keep them rich so they can have the means to keep their people under control and and keep an eye on Iran.