Okie Dokie, so let's see if we can sum up this discussion for the benefit of Andy7 the OP

It's perfectly acceptable to write a song that is influenced by and respects the tradition (accepting the fact as correctly stated by Dick above that there is no 'one tradition')

And it's perfectly acceptable to describe that song as a 'song in the folk idiom'

Tell you what, in the interest of plain english, that the mass population might understand, let's simplify that description and call it a 'new folk song'

who knows, maybe when we've got used to that, we could simplify it even further and just call it 'Folk'

Perhaps then we could remember just how much has changed in 60 years, call it the 2014 definition, and then come back here in another 60 years and argue about it!