Different types of "contemporary folk"?
How about:

Newly composed
1. Instrumental/choral compostions for several voices
2. Songs/tunes that cannot sensibly be performed without instrumental backing.
3. As 2 above, but suitable for dance, modern or traditional/social
4. Songs/tunes that can be 'performed' by one person, the tunes not necessitating an instrument, but can be whistled or hummed.

I was tempted to mention copyrighting. A composition can hardly be regarded as "folk" if no-one is free to play it. But equally, if no copyright is claimed, it is easy for the commercial world to exploit this; which doesn't prevent the "folk" connotation, but is manifestly unfair. So to be "contemporary folk" there has to be some freedom for others to perform, but not necessarily profit from, the new work.

Jim, the original "Birdie Dance" - the Canary - has never become "folk", even though well known in the early dance movement (but don't they make it so SERIOUS). So I doubt the modern one will!