"If, for example, "Mr Tambourine Man" is around in a few hundred years, will it be folk? If not, why? And if so, then why isn't it folk today?"

That problem will most likely solve itself Peace. In the most unlikely event that "Mr. Tambourine Man" is still remembered by anyone a hundred years from now, the population at that time will doubtless have their own definition of traditional, as no one living will be as close to, or as affected by, the oral tradition as we are.

Two of the oldest pieces in existence cannot, by some definitions, be called "Traditional", nor according to the 1954 definition, "Folk", since they were published by clerics of the time, on parchment.

How many here would define "Summer is Icumen in", or "The Cutty Wren", as neither traditional, nor folk.

Don T.