I think that's way overstated. The Saudi populace has seen what civil war looks like in Libya and Syria. I doubt they're in any mood to replicate that. The average Saudi got a huge bump in living standards when oil prices went to $!00 and state spending jumped in tandem. I expect he understands that when oil prices tank, spending will have to follow. Besides, there are any number of commodity exporters where prices have tanked and belt-tightening ensued (in Africa and Latin America) without triggering regime-ending armed insurrection.
Libya and Syria were special cases. Without foreign aid, both of these rebellions would have been strangled at birth. Libyan rebels benefited from NATO intervention, just as Gaddafi was about to finish them off. Syrian rebels had the benefit of open checkbooks from the Gulf kingdoms bent on turfing Alawite apostates from their perches. Assad was also in a tough situation because Alawites are regarded not merely as infidels, but apostates (i.e. subhumans deserving of extermination, based on Koranic edict), ruling a majority Muslim country.
That may be true, but there are powerful forces against SA. The Saudi monarchy is a British artifact, not an islamic one. Just as progressives want to erase history here, ISIS, Turkey, and Iran are working to control the islamic narrative. In each of those three narratives, the Saudi monarchy has no right to exist. When one of those narratives becomes dominant, the monarchy can be swept away as easily as the confederate flag.