Let’s say Aerys is less crazy (yeah, yeah, but bear with me). Rhaegar “abducts” Lyanna Stark. Then Brandon goes to the Red Keep and shouts for Rhaegar to “come out and die”. How would an intelligent king diffuse this situation, or at least keep it from spiraling into rebellion?

Given Aerys’ conflict with his oldest son, I’m honestly surprised he didn’t use the moment to gains support from the Starks et al. by disinheriting his son Rhaegar, promising to return Lyanna Stark to Robert Baratheon, and then engaging Viserys to Rhaenys to keep the Martells on-side.