Ho, folks! This seems to be a "what is folk ?" thread under another name.
I have never been satisfied with the "criterion of ignorance" for defining "folk" music. (This is the notion that folk music must originate among people who are unaware of distinctions between folk music and any other music.) Hence for me the songs that were collected in low-population rural areas are part of a continuum, and certainly not a closed canon.
One way I like to identify "folk" music is as music that circulates freely (no friction from copyright cops) as short one-line diationic or only slightly chromatic airs of fairly consistent tonality throughout (no fancy modulations or schmaltzy chromaticism.) Folk music, in this sense, can be an ever-expanding genre, as long as the term of copyright is short enough to allow a reasonable rate of turnover from copyright to public domain status. If that condition is met, folk music, as here defined, has a future.