One of the components keeping the US Dollar as a global reserve currency was the agreement between the United States and Saudi Arabia to price oil in US Dollars. As the regions largest producer, this caused other oil producers to follow suit, and forced customers to use USD if they wanted oil. Of course this is not the only thing supporting USD hegemony but it certainly supported the USD as oil is the commodity that runs the majority of the industrial world.
Saudi Arabia has recently warned of a ‘shift’ away from the US supposedly because of anger over Syria and Iran, but is that the real reason?
Saudi Arabia has warned of a shift away from the U.S. 
Here’s the real reason: China just dethroned the U.S. as the world’s largest importer of oil.
As Oil Price notes :
Last month the world witnessed a paradigm shift: China surpassed the United States as the world’s largest consumer of foreign oil, importing 6.3 million barrels per day compared to the United States’ 6.24 million. This trend is likely to continue and this gap is likely to grow , according to the EIA’s October short-term energy outlook. Wood Mackenzie, a leading global energy consultancy, echoed this prediction, estimating  Chinese oil imports will rise to 9.2 million barrels per day (70% of total demand) by 2020.
Last year China became the world’s largest trading nation, surpassing the US for the first time. Now China has surpassed the US as the world’s largest oil importer. This combined with the news about a potential Saudi ‘shift’ away from the US is not likely a coincidence, considering the rapid proliferation of Yuan swap agreements.
People’s Bank of China (PBOC) has signed nearly 2 trillion yuan worth of currency-swap deals with 20 countries and regions, including Hong Kong. Here’s a breakdown of happenings:
- Earlier this month, the European Central Bank announced a large currency swap arrangement with China. 
- An Asian ”renminbi bloc” has been formed involving seven countries.
- Russia, Iran, Angola, Sudan and Venezuela have converted oil sales to China into the Chinese Yuan. Worldwide, we see more than 5 million barrels per day traded in Yuan rather than U.S. dollars.
- Thechinamoneyreport.com  on June 16 reported RMB-yen trade is growing strongly a year after launch.
- BBC News, April 9: “China and Australia in Currency Pact “
- BBC News, Feb. 22: “UK and China Poised for Currency Swap Deal “
- BBC News, March 26: “China and Brazil Sign $30bn Currency Swap Arrangement “
- Thechinamoneyreport.com  on June 4 reports that Singapore has launched a Yuan clearing service.
- Although ignored in the U.S., there has been increased chatter among foreign media about the RMB (aka Yuan) reaching safe-haven, reserve currency status, as Asia Today  reported on July 22.
The Saudi position has always been relatively simple, maximizing their oil revenues and security. With the Yuan now being used globally at a rapid pace, and China being the world’s largest oil importer, it’s no surprise that Saudi’s are ‘shifting’ away from USA.