To me, I think the problem is, how she dies and how well known it is, or how fast its proven as to what the effects will be. If we get some sort of wheel of time duel between the protagonist and the great evil projected across the sky for the world to see, then I think the matrons are in for a very bad time as the have nots arent going to be very easily restrained when they literally SAW their goddess get decapitated or whatever. If its a quiet thing where one day the matrons realize their magic isnt working, they will likely, as you said, be able to bluff for some time and possibly find a workaround before things boil over.