My view is that the intrusion of mass media coverage of youth culture is what kills it (mods, rockers, northern soul kids, ravers - it's happened time and again). The MASS influx that results from exciting/edgy coverage in the press inevitably blurs the boundaries and waters down the most hardcore features of a youth cult as 'eager amateurs' join in without any feel for the the more deeply held 'secret truths' that underlie and define a particular group.
Whilst that sounds elitist it isn't as much as it sounds - when someone comes to the northern scene (or certainly when I was able to go out more often than I have birthdays) who is recognised as 'right' they'll get grabbed and DRAGGED into the core RAPIDLY (have seen it a good number of times), no matter how young or inexperienced they are.
Modern media also tends to homogenise scenes - so you'll see people picking and mixing different elements from very different youth groups; so you'll see people who look like rockabillies at allnighters, kids looking pretty moddy who are into house and so-on. This was always the case to some degree, but in the past these people were rare exotics. Nowadays there seems to be a big chunk of kids who are just into 'stuff' without the mad, obsessive allegiance to a single music form and street style that is essential to develop the essential hardcore that drives the wider group as a whole.
All-in-all I think sadly the days of the old youth cults are now gone because music has lost its hard genre boundaries and kids absorb too many different influences to become militant followers of this or that style and to a large extent many of them simply look like younger versions of their mums/dads again... When I was younger I always used to say that I respected headbangers and bikers FAR more than the local chart disco kids - even though in my home town us scooterboys were often at war with them - because at least they were REALLY into what they liked.
I always used to say I thought that northern had many of the features of a religion - the whole 'keep the faith' thing was never completely tongue in cheek.
Dx