"they felt they had a secure living. they thought folk clubs and folk music was going to be constant feature of the post war music scene."

Perhaps their mistake was in believing in notions that the revival would be as enduring as the very tradition of folk song that it sought to emulate and revive?

As for the evolving or otherwise of "folk" into non-traditional acoustic 60's pop, unlike traditional folk music itself (which came from and belongs to another world in time altogether) what "folk music" became during the 60's, was inevitably forever destined to be "60's acoustic folk"

Most modern styles of music become dated very fast and while 60's acoustic folk was "modern folk music" in it's day, it's now simply dated 60's folk music. A thing of either cringing embarrassment or misty eyed nostalgia for those who were there depending on their perspective, but of little interest to anyone who came after bar music nerds who enjoy trawling through back catalogues. Same deal with 50's rock'n'roll or 70's prog rock or 80's new wave..

So overall, as for what folk music has "evolved" into and those various "folk" activies I've been to If I had a hammer, someone else would be leaving with a fucking head injury...