I read Orchestrating the Nation a few years back, so I am aware he's got a book he's plugging. I'm also more or less up to speed on the Future Symphony Institute defense of the time-tested popular and established symphonic canon counter-argument.
The various canons throughout the arts are like crowdsourcing. These works are the best of the best and actual people over the ages keep voting for them without ideological intent. Seems pretty democratic.
It's not that that isn't a compelling argument, actually, it's that I wonder if the FSI crew would consider it as compelling if the massive and persistent popularity argument were applied to someone like Michael Jackson, Stevie Wonder, Elvis Presley, David Bowie, the Beatles or the Rolling Stones.
Not so sure the "these are popular time-tested classics" argument would be as readily accepted.
I'm more into classical guitar (obviously) and chamber music myself, so I would be curious to hear Florence Price's string quartets if those ever end up on a CD.
This kind of thing still interests me, though, because we had Scott Joplin's centennial last year (of his death) and ... even though Joplin's music has obviously had an influence on culture there wasn't much of a centennial for his music. Ethan Iverson had a centennial observance for Lou Harrison (hey, why not, Oregon composers need some love) and Thelonious Monk (hooray!) but ... not Scott Joplin. Is Scott Joplin too lightweight for serious musicologists and musicians to pay homage to the beauty of his work? One of the problems may simply be that ever since the long 19th century only those who can be taken "seriously" are apt to be given a serious consideration.
Which in several ways gets back to whether the musicians noted above, in the not-symphonic department, would ever pass that test. As I get older I begin to appreciate the artistry of musicians and bands who in my twenties I not only couldn't get into but actively disliked. There's nothing like hearing a slew of Katy Perry songs to make me feel like, you know, Whitney Houston was just all around better than this stuff. I'm also way more appreciative of Hall & Oates in my forties than I was in my twenties. What changed was the nature of the out put of the song machine and as I've gotten older I suppose that it wasn't going to just be enjoying more Xenakis and Messiaen that was going to change. "How Will I Know?" is a tightly constructed and elegantly straightforward song. It sure beats the pewling of Vance Joy.
Bringing this back around to being a guitarist, given how expensive and entrenched the symphonic repertoire is, I would propose that it may be easier to add women to the canon of Western music in other contexts. Joan Tower's string quartets, for instance, are well-made pieces. I was waiting a decade for someone to finally record Incandescence.
But it's on the guitar that I can think of a few composers whose work has really stuck with me. Annette Kruisbrink's chamber music for doublebass and guitar should be the cornerstone of anything resembling a canon for those two instruments. Nadia Borislova's Butterfly Suite is a great piece, and she's written some music for clarinet and guitar I've thought about writing about over the years. If on the one hand the symphony institutions (pun intended) are not so open to women and people of color being just added to the canon willy nilly we guitarists need more than just the same old transcriptions of Bach and Albeniz to play decade after decade.