Here's a philosophical question? Are traditional-based clubs preserving the performance of traditional music, rather than the music itself? In these days of recorded sound, written records, archives both printed and digital, resources far more readily available than before - with banks of material noted, recorded, indexed, digitised - and more to be available - it's not the preservation of traditional songs that will be lost. More likely the act and art of performing them that might be lost or overwhelmed. What has been lost, to a greater extent, is the fluid nature of the songs as they were passed from generation to generation. The process of "collection", with all the attendant documentation and academic discussion, probably - and ironically - helped to end that. But I wouldn't say that traditional song is either fragile or vulnerable - whereas the continuing performance of it may be.