Saudi Arabia reached their Hubbert curve apotheosis probably in the 80's (their proven reserve is a state secret). They've been desperately trying to handle this fallout ever since.

Russia, OTOH, is the real the mother of all petrostates. Any problem you might imagine facing Saudi is tiny compared to the impact on Russia. They've already suffered so much as a result of the oil crash in the late 90's by becoming a mafia state.