Although it's true Shanks desires order and stabilization, protecting the three great powers from collapsing, it seems like as if he's waiting for someone/something to reach a certain level, waiting for a trigger to quickly destroy two extremist sides (BB Pirates/WG which represent Havoc/Order) with one stone (Luffy). i think when Shanks was a child during his time with the Roger pirates decades ago, Roger told him about the God Valley incident and that he joined Garp to stop an evil pirate from ruling the world which saved the world nobles, Shanks fully understood Roger's reasons and why he did that.
After fighting kid Teach, witnessing his amnesia disease and receiving the wound on his eye, Teach told him about his goal to manipulate the great powers and surpass Whitebeard whom he despised because he never tried to become the pirate king despite him being able to. Teach's plan involves stealing the three strongest devil fruits in each class, reviving the rocks pirates whom he admired by collecting a band of the worst criminals and getting the three ancient weapons to destroy Mary Geoise, putting the world nobles' lives in danger like it was in God Valley.
Shanks became wary of Teach and considered him as someone who could potentially threat the balance itself like Rocks D. Xebec did, especially after Teach took down Ace, the late pirate king's son whom Roger himself sought to be his heir. so Shanks is trying to minimize the casualties Teach/other stakeholder do. warning Whitebeard, stopping Kaido, stopping the summit war, alarming the five elders etc.. However Shanks' true goal is to indirectly manipulate Teach and the marines into chopping each other during the final war until a third stakeholder (Luffy) emerges and deals the finishing blow to both.
So basically, Shanks made a bet on Luffy when he lost his arm before Luffy going on his journey, and that bet is for Luffy to be the next Joy Boy that would neutralize Im-sama and the future "Xebec" using the different allies he managed to befriend during his journey and the three ancient weapons. Shanks' actions are simply to ensure that Teach/Yonko/World Government are kept in check/deadlock and that none of them are able to wreck the other until endgame when Luffy becomes strong enough to finish them all.
So yeah, it's laughable how this important plot could be all according to a simple bet from a 39 year old snitch
