It's hard to say. When I've talked to him lately he denies any real problems. But his problems did return after a long remission. And he has been doing chemotherapy--mostly oral. Dancing is done for now. He's been traveling with a band in the bus---a few less minutes for him to need to be the center of things.
At the same time, though, he's been appearing with the trio of Hartford and Mike Seeger and David Grissman. It seems like a strange mix--but those guys are all musical geniuses and if anybody can make it work, they can.