It betrays no lack of faith to say that new musicals are on the skimpy side of Broadway this fall. Given the deserved box-office and critical hysteria around "Hamilton," which opened in early August, one may be forgiven for imagining producers singing and dancing down Times Square in celebration of all the brilliant new musicals.

In fact, there will be just three more new shows before the end of the year, and none has opened yet. Naturally, we hope for nothing but the best from "Allegiance" (George Takei's family story about Japanese-Americans in World War II), "On Your Feet!" (the Gloria and Emilio Estefan story) and "School of Rock" (Andrew Lloyd Webber's adaptation of the movie).

But far less obvious, at least at the moment, are three potentially important new musicals percolating for upcoming Off-Broadway openings in nonprofit theaters. And, though it is impolite in some circles to suggest artists are even thinking of a commercial future, this could make for a lively Broadway spring.

As we speak, David Bowie is huddled in the New York Theatre Workshop's East Village rehearsal room polishing his score for "Lazarus," a musical inspired by the same novel that led to Bowie's dazzling 1976 screen performance in "The Man Who Fell to Earth." The show, which sold-out its initial nine week run for this 199-seat theater in three hours, stars Michael C. Hall. Its book is by Enda Walsh ("Once") and is staged by the most talked-about maverick director of the season, Ivo van Hove, in his eighth production at NYTW and about to make his Broadway debut with "A View from the Bridge." "Lazarus" begins previews Nov. 18 for a Dec. 7 opening.

Meanwhile, in the Atlantic Theater Company's Chelsea home, Green Day's Billie Joe Armstrong, co-author of the Broadway adaptation of the band's "American Idiot," is polishing an original theater score for a show called "These Paper Bullets!," which began at the Yale Repertory Theatre and has been further developed here. The show involves a Liverpudlian supergroup with a psycho drummer and, somehow, Shakespeare's "Much Ado about Nothing." It starts previews Nov. 20 and opens Dec. 15.

And at the Second Stage Theatre in Hell's Kitchen, Broadway baby Diane Paulus ("Hair," "Porgy & Bess," "Pippin," "Finding Neverland") has left her usual stomping ground to direct "Invisible Thread." The musical, titled "Witness Uganda" when Paulus first staged this at her American Repertory Theater in Cambridge in 2014, follows a young New Yorker as he volunteers to work in Uganda. The show is in previews for a Dec. 2 opening.

It is safe to say that today, perhaps more than ever, Off-Broadway and nonprofit regional theaters are essential to the development of serious new musicals. The old tradition of road tryouts is too expensive and unwieldy. So really, what theater board wouldn't be pressuring its artistic staff to find the next head-spinning "Hamilton," the next Tony-winning "Fun Home," the next way to reinvent the American musical theater in creatively audacious -- yet, you know, moneymaking -- ways?

All three productions have what is known in the business as "enhancement money," which means investments from commercial producers hoping to be on the ground floor if the show moves. Once upon a time, not that long ago, such support was more of a hush-hush operation. Nonprofit theaters got their nonprofit status by, theoretically, eschewing the corrupting influence of programming with one eye on commerce.

Of course, that was before the Public Theater broke the mold with "A Chorus Line" -- not to mention "Fun Home" and "Hamilton." It was before New York Theatre Workshop gave the world "Rent," then "Once" and "Peter and the Starcatcher," the Atlantic dared a mass audience to embrace the boundary-pushing "Spring Awakening" and Second Stage sent "Next to Normal," which won a Pulitzer.

I ask James Nicola, NYTW's artistic director, if it sounds quaint now to argue that these hits betray the original nonprofit mandate. "Oh, yes," he says laughing. "You have to learn to survive commercial influences every day," he continues thoughtfully. He says that many in the not-for-profit sector -- including hospitals, universities, museums -- "are being challenged to behave more like for-profit entities. If we want to exist, we have to make our peace with it."

Nicola's theater will also face the happy hot-ticket dilemma next season with Daniel Craig and David Oyelowo in "Othello." Nicola talks about staying "true to your mission," which, based on the years of provocative work there by such masters as Caryl Churchill and Tony Kushner, doesn't sound a bit self-serious. He worked with Joseph Papp at the Public in the '70s, during the "Chorus Line" bonanza. "Day to day," he says. "I watched him invent a dance of integrity through mine fields. That is the inspiration I have."

I reached Neil Pepe, artistic director of the Atlantic, while he was seeing theater in Cuba. In a couple of cutoff phone calls and, finally, a text, he, too, talks about the importance of "our mission" remaining "fully centered on serving the story . . . " and "allowing the piece to artistically blossom in a protected process-focused environment."

The quality of the shows coming out of these theaters depends, too, on a continuity of relationships with artists. "These Paper Bullets!" is written by Rolin Jones, a playwright who has worked several times at the Atlantic. "We have always loved the idea of integrating contemporary rock and roll and great playwriting," says Pepe without having to mention how wonderfully that worked in "Spring Awakening." He savors the combination of "the genius and originality" of Armstrong's songs with Jones' adaptation of Shakespeare, The Beatles' London. "It's a great combination for Beatle fans and lovers of Green Day."

Carole Rothman, artistic director of Second Stage, has seen both sides of producing with an eye on Broadway. She had what she calls an "unpleasant experience" with a producer who decided to go straight to Broadway with the musical version of "American Psycho" instead of starting it at her theater.

"It was at the very last minute," she says, adding that the disaster "came with a massive silver lining. People realized we had an opening and sent us a lot of interesting material."

She read the book and listened to "Invisible Thread," and remembers thinking, "Whoa! This is special." She says that Paulus wanted to do more work on the production staged at A.R.T., that the director wanted to add a character and other work there wasn't time to do earlier. "I'm always looking for potent emotional stories," says Rothman. "I like thorny work -- something smart, funny, thrilling."

Sure, everyone is looking for the next "Hamilton." Meanwhile, however, Nicola has an optimism we don't often hear from theater people in the day-to-day grind of it. "The American musical theater is really alive," he says. "It's not just the same old thing being repeated." Chances are, if any of this ends up on big old money-making Broadway, we'll profit, too.