The colLector has to make a decision,He has to decide what he thinks he should be collecting.CecilSharp did this.
many collectors today, collect only from source singers who have learned their material by ear, from their family,and from those who have not been involved in the folk revival,sadly in my opinion,some of these singers are not of the stature of Phil Tanner,Harry Cox,or Sam Larner, Walter Pardon,but they are still collected regardless of musical merit.
one or two of these collectors,then hold the folk revival,at arms length,and treat revivalist singers as if they were lepers.,
but collectors wont record the likes of Tom Sydall,because he is writing his own material,they appear to have an attitude that it must wait 200 years[till the writer has been forgotten].,
perhaps the song has to be changed by the people[regardless of whether its changed for the better]for them to deem it worth collecting.
ofcourse there will be no new traditional songs eventually only composed songs wriiten in traditional style,collectors of traditional material will become extinct.