Jim,your post tells me a lot about yourself.
all the singers you mention are unacccompanied singers.
I too can listen to a good unaccompanied singer for a whole evening providing they vary their material, tempos,keys,and story of songs.
I am also quite happy to hear skilfully accompanied traditional/modern[ with trad influence] songs.
I think that the unaccompanied singer[because he/she is relying entirely upon the voice]has to be very conscious of good presentation of the material,has to be able to stimulate audience partricipation[ maybe30/40 percent chorus songs],because many modern audiences are not familiar with unaccompanied singing,and might find an hour of it ,hard going.
I do not believe the folk process is dead ,it may change,the way we acquire new information may change [via the computer, even learning by ear via the computer],but people will still go on learning the old songs,as well as modern songs.Dick Miles