You make an excellent point. The romanticism does tend to fade somewhat overtime and jihad has probably exhausted itself somewhat for now..... In the case of the Saudis, we also have a jealously of the haves and have nots and a tiredness of corruption, otherwise known as the arab springs, or the earlier talib effect in Afghanistan.AQAP are busy in Yemen, one of the drivers for the KSA/UAE invasion. It and its predecessors are the biggest internal terrorist threat. They're still active in the kingdom and periodically there's a shoot out. What happened in Syria has been sobering for the populace at large and has totally shattered any romanticism attached to jihad. A fortunate and purely co-incidental benefit is those who felt inclined to have a bash haven't generally returned as they did from Afghanistan, mainly due to being severly dead.
There hasn't been much in the way of shia terrorism, dissent yes, AQAP and its predecessors were always it though they may have assisted Iran/Houthi with the latest cruise/drone attacks. Iran was facilitating AQ way back, because they were the guys to do stuff in kingdom.
Pressure for change is the same as in the other ME dictatorships/repressive regimes (including Iran) and comes for the visions they see of the West and elsewhere. The Arab Spring hasn't died, see Egypt. This is what MBS is most worried about.
The original query; I tried to answer, was why the KSA have mercs on the frontier and why they couldn't redeploy troops from internal security. One assumes another very large order for ordnance will be in the pipeline(pardon the pun) as we speak.