Well blonds are usually said to be more attractive.
Since ice age they have been more wanted then normal brown haired girls.
With ages to come natural blond hair and blue eyes will die away.

They will meld in with the brown haired to create a Grey mix;
The children born with this ‘no color’ unattractive hair will bleach and color their hair, trying to feel pretty.

As time goes the chemicals will kill their hairs and a new generation of hairless people will be born…