One method to keep super long hair healthy is to trim the ends every 2-4 years. If she continues this her hair will be nearly as thick at the ends as at her scalp. If she babies her ends her hair will be super long - super thick - and super healthy to the ends all at the same time.
Shes doing the right thing and her marvelous long hair will continue to grow.
With all respect to the Longhair Goddess Anya!