Seems to me that nobody defined traditional song, so lots of effort has been spent on arguing "around" the issue. Does it have to be sung in the original setting (whatever that means) to be traditional? Does it need to be sung in some "traditional" manner (whatever that means)? Is folks song, as Anna Russell once defined it "the uncouth vocal utterance of the people? Is traditional song to be defined as associated with the British Isles and the import of that tradition into America? All of these issues were discussed somehow, but with little attempt to find a common starting point from which discussion could proceed.

All that said: All one needs to do is consider a couple of Bill Staines songs "All God's Critters" and "River" to know that the tradition of creating music that can enter the main stream of music transmitted orally (or aurally if you prefer) today just as Stephen Foster songs entered that tradition in the past.

As to the other question of whether COLLECTION of traditional song is finished. I doubt it.