Well, there is a difference between popular and folk music.   Reaching a lot of people is not the true definition of folk music, but I do understand your point as it relates to music from the folk revival.   I do feel that there are songs that have reached a folk community, and in many cases beyond, in the past 25 years.

Six songs that stand out from the last 25 years would include -

From A Distance
Swimming to the Other Side
You're Aging Well
Love is Our Cross to Bear
Luka
Another Train
When I Go
Broke Down
Seven Bridges Road

okay, that is more than 8 - and they might not be songs that everyone is familiar with. Still, I believe these are songs that are representive of the great writers and performers that are working today.   Reaching the largest group of people is not the only way to be successful. Britney Spears can wiggle her ass and sell a million copies, but it doesn't make for a great "folk" song.