You have to remember that Woody was a TOPICAL songwriter. The Archives have thousands of songs that Woody wrote on all types of topics. The labor movement may have been the defining social cause of his day, but he would have been singing about many things today. IF Huntington's hadn't robbed him of his life, I am sure he would have been singing out loud during the civil rights movement, perhaps Vietnam, ecology, etc., etc., etc.
As Woody said - there will always be folk music because there are lots of folks. To paraphrase, he would have always found a topic to sing about.