It's a crisis of their own making, they're literally cutting their nose off to spite Iran.
Still, this was going to happen one day, it was inevitable...if not because of reduced demand then because of Peak. The Saudis have a helluva lot of cash squirreled away in assets and such. I think I read somewhere that they have a reserve of $900b. Of course, with the lifestyle that their Princes lead that's probably enough to last a week...
But yeah, Platapus is right, the US will bail them out eventually, because no one in the GOP would stomach the US siding with Iran on anything so the US will have to side with Saudi Arabia against Iran in the coming Middle Eastern cold war.