Sharon Terlep of the WSJ reported here
that GM stated today that they are close to a fix that will make the battery safer in crash. Click on the Video to hear the discussion of this.
Frankly, this will be a waste. This crash is already at the limits of what a car/human can sustain. They are throwing a car sideways into a pole. The car is totaled after this event. Why build a strong box to go around the battery to survive this event? The car is toasted after this. Just adding weight and cost which is not necessary. If the battery takes days and weeks before it lights up that is plenty of time to extract survivors and discharge the battery.