There are modern songs that would translate well into the folk idiom. Of course they would not be folk songs, but they'd still be fun.

What about the Old Songs that have been translated into a Folk Idiom? Are they not folk songs either? In fact, once a song is sung in a Revival Context, and in the Idioms thereof (which, of course are not folk) maybe it ceases truly to be a folk song, seeing as the person singing it is not truly a folk singer, but merely an interpreter of folk song. It's a dead end, no longer living, no longer breathing, no longer capable of reproducing itself in any way that isn't likely to result in hideous mutations rather than pure-bred variations. Similarly once a song is collected, it ceases to be a folk song, but rather just one of an infinite number of possible variations that a folk song can give rise to in it's natural habitat, each one apable of reproducing itself, yet never once repeating itself and entirely innocent of itself, much as the singers of such songs were innocent of being folk singers until they were told otherwise. Once they became folk singers their purity was compromised and the whole thing tainted.

The solution is the enployment of invisible multi-dimensional time-travelling folk song collectors who are able to collect the songs as and when the singers sing them, and thus follow the Lives of any given song from its seed vision to its eventual branches, thus giving us a better idea of how these things happen. By chance, by design, by way of purposeful creativity or just entropy after all. As time travel's a long way off we must make do with what we've got, but then again maybe we're surrounded by invisible time-travelling folklorists and anthropolists as we write, eagerly collecting our every utterance.