My own teenagers didn't seem as 'in to' a particular type of music as I did as a teenager.
Other way around
I think there was no impact and fill that gap they made a new impact
But with the proliferation of alternate media forms the youth are not grouped into as large factions as before because the number of music forms and groups is much greater. In the 60's most youth listened to mega groups like the beetles. But today there are no real mega groups but many different groups.
It's going to influence their fashion choices for sure... beiber fever is much the same as madonna frenzy was in the 80s.. and let's not forget the whole spice girls thing of the 90s *shudders*