Seems simpler to me than all that. The question will be whether those songs are sung by anybody in 50 years time and why.

All sorts of stuff was sung in the 60s and 70s purporting to be "folk songs" but we're now 50 years or so down the line and it's looking as though "Blowing in the Wind" is still being widely sung by people and so are some Beatles and Kinks numbers. In my session, we sing "Kites" by the Simon Dupree and The Big Sound. Certainly didn't seem like a traditional song at the time but it may well become one, at least in parts of Hertfordshire. The test is one of whether people continue to sing things over a longish period.

In the heyday of the traditional "singing pubs" of Suffolk people were singing material from as recently as 10 years ago.

As I've said earlier, I don't go to folk clubs much. Seems to me they often have a biased idea of what is "folk" or "in the tradition" or "in a traditional idiom" whereas what people do themselves in their groupings in more traditional surroundings may well be very different.

:-)
Ian