Your wife isn't going to change ANYTHING until she sees the need herself. We shall all hope that if a situation occurs, she is lucky enough to survive.
You know what they say about horses and water.
Also, after many years of wearing high heels, she may not be ABLE to wear anything else. Often, the tendons in the back of the leg contract from not being used, and the person just can't walk in flat-soled shoes.
Sue