My instinct is the tradition is safe because key 'texts' (to use a functional neologism) were saved by collectors and exist in every digital, aural and hard format conceived. So the embattled stance folk has adopted is largely a stylistic trapping made popular by the revival.

Those songs come alive by performance but are vital enough to have sprung a continuance of the material which may or may not have anything to do with original broadsides and ballads. Indeed it is possible (and quite likely) to hear traditional material that by familiarity or institutionalisation has none of the spirit of folk (much as a prayer is muttered in a church service with no sense of the word's meaning) while hearing renditions that are historically inauthentic which are imbued with the essential matter of folk.

That matter is mercurial, I believe its elusiveness is somehow intrinsic to it and won't be categorised by history or musical virtuosity. It is some deep and direct utterance of the soul that can only be perceived when it is heard and defies language and music, which is why the national boundaries of folk are inventions. Folk may speak to one community more than another but is essentially universal.
I'd suggest that the Victorian obsession with taxonomy did a good deal to reduce the impact of this common sound and to create boundaries that still exist today.