If she keeps falling at her current rate, she isn’t going to live another 10 to 20 years no matter what the cause of the falls are..
Depends what risks she takes and how she falls. I have some experience with a patient with seizures and those falls can be bad. No control at all and a good chance of smacking your head hard on the pavement. The Parkinsons falls are all conscious and thus yield broken wrists, broken hips and cracked vertebrae. With Parkinsons such injuries take 2-3 times longer to heal and can greatly diminish the quality of life. Usually not fatal but can be fatal.