Well that worked out well for the Saudis. A virulent Shiite theocracy.
It did work out well for them so far.
With the Shah gone, the Saudis became the US partner No. 1 in the Islamic world. Saudi influence since 1976 has been metastizing in the entire Western world.
And with the Revolutionary Shia regime in Iran the Saudis had ab easy pretext to push the US into isolating and keeping down Iran as a rival to the Saudis. In the same vein they had Saddam drag Iraq and Iran into a decade of war, which again chiefly benefitted the Saudis.
Now since 2003 Iran more and more emerges again as a regional power and seriously causes worry for the Saudis.
Iran has the potential (if unleashed under proper leadership) to be the Mid-East power #1. The Saudis will always remain a desert sh*thole with shiny toys.