People will simply stop mining until it is profitable again and no doubt people who have access to free or extremely cheap electric will continue to mine so it will not stop completely and as others have pointed out it is a self correcting system so the difficulty will reduce to make it attractive to mine.
Its true, i am believe miners like others bussinessman. They will calculate the cost and the bitcoin price and if the price below production cost, they will shutdown the production until the price getting better.