The Saudis have already entered a mutual defense pact with Russia
>>>It's just a fancy title. Dollar is the reserve currency, but Euro, Pound, Yen, etc...
Actually it isn't, that is why sanctions work so well, Russia and China just entered into an agreement to trade directly between themselves without converting to USD first. It wont be long before Syria, Iran, North Korea, Argentina, Cuba and several African nations join the fray. Not to mention a large number of other out of favor political leaders that are sick of US led regime change or coup attempts constantly testing them..Think Bolsonaro, Duterte, Aung San Suu Kyi.
These are the countries that hold the resources needed for a productive world and soon enough the rest of the world, including the West will be forced to follow them into an new non US hegemonic world, regardless of the number of guns and bombs Uncle Sam has.