So I hear a lot how the blonde trait is carried in a recessive gene. Supposedly blonde people will no longer exist in the future as a result. How reliable is this claim?
In the populations where it is significant it has been selected for in the past (had survival or reproductive advantage). As these are large populations it should stay there in them in stable proportion unless it is selected against. Which it is to an extent outside Northern and temperate climes.
However as well as that, if these populations mix a lot with others the frequency should decline but not to 0.