if Strong economies like GCC want they can have their own independent currency, not attached to dollar. May take a while, but it is very much possible and it seems like this will happen in the near future as I don't think dollar will stay a good option in a few years time.
Saudi Arabia Alone owns around 3 trillion dollars worth of bonds and other investments in US Banks. However I can't guess if they have the courage and strength to take it out.
But if they do, US economy is doomed and so is Dollar.