The monarchy has been blessed in so many ways and eventually they are going to have to answer to their people when things turn for the worse.
Ultimately I hope any political change in Saudi Arabia is towards the democratic side and not a wahhabi, fundamentalist regime that makes the monarchy look tame in comparison.
We will see a more unpleasant regime replace the Saudis, but lucky without money they will be mostly harmless.
Considering whatever regime takes over next will have access to one of the largest and most easily accessible oil reserves in the world...I doubt they will have trouble funding whatever dubious operations they end up being involved in. We don't know what the Saudi oil reserve is, it have stayed stable because they claim to have found new reserve every year equaling to what they extract, the question is whether that claim is true, or they just tell that to avoid trouble.
The problem is that there's no average Saudi, there's the tribes in the centre which the regime are based on, who make up the national guard (the only Saudi force worth anything), they're arch-reactionaries, and the potential problem. When there's the eastern Shia who live on the oil rich east coast, who are kept down by the regime, if SA collapse, they will likely rise up, but like the Shia in Iraq, they tend to do badly in war, but they will likely receive Iranian and Iraqi support. When there's the West Coast Sunnis, who are impoverish, but rather cosmopolitian and modern, I woudn't call them secular, but they're preferable to tribes inland. At the Yemenitte border, there's Shia again, they're also kept down, but if the regime show weakness, they will rise again this time with support from the Houthys in Yemen, for some reason they're tend to do well when they rise up, and it's doubtful whether a post-Saudi regime could beat them, even the Saudi today risk losing to them, especially if the Houthy intervened.