From a nice profile in Paste, Martin discusses the curremt state of bluegrass:
Martin points out that in recent years, "bluegrass's role has become much more open to experiments," but also noted that he and the Rangers included a version of "Santa Fe" without the trumpets for the "hardcore bluegrass stations," just in case.
But he is adamant that there is ample room for innovation in bluegrass—which traces its history to the roots of Appalachian string music and early American jazz—as well as with the banjo itself.
"It's become an extremely sophisticated instrument thanks to players like Bela Fleck, Noam Pikelny and Tony Trischka," he says. "Bela Fleck's writing concertos for the banjo to be played with an orchestra. So the banjo is in a different place. It's getting the word out that's a little difficult, because it's complex. The banjo is very complex, especially when played three-fingered. Clawhammer is generally more melodic and accessible for a lot of people."
There's even a nice vinyl album option that will only get better with time.