The replacement of those methods by broadcast and recorded music stopped the folk process happening - those traditions aren't evolving, because there's nowhere for them to do so.

The folk-process is a conditional fantasy on the part of the people who believe in the integrity of what is, after all, merely a concept. It is an article of a faith that has no objective currency outside of those who hold it to be a self-evident truth which is, self-evidently, not the case at all. Traditions are evolving with the musicians who are out there singing and playing the stuff whatever their sources might be. Every time you sing a song you are, in fact, evolving it if only to suit your requirements; in so doing you are no different from any other Traditional Singer at any other point in time. Now, this is an observable phenomenon; I see it all the time, we all do. It's in the organic nature of the universe that nothing stays the same, and nothing can ever happen the same way twice. If traditions aren't evolving its because our concept of The Tradition is out of keeping with the reality of the tradition, which isn't something that's going to roll over and die just because its easier for the 1954 Faithful to deal with a corpse.