I don't think it's necessary to introduce "new music" as "legitimate folk". You'll just end up having arguments with people about definitions of folk music - there's too much of that already.

Most traditional folk singarounds are strong enough to incorporate non-traditional material. Some of such non-traditional material sits happily enough within it that it will eventually (in 50 years' time, say) become traditional material. I sing Gillian Welch's 'Miner's Refrain' unaccompanied at singarounds and everyone assumes it's traditional.
We just have to wait long enough for the majority of people to forget who wrote it.