Even for Richard Linklater, who famously shot a little bit of “Boyhood” each year from 2002 to 2013, his “Merrily We Roll Along” is ambitious.

Linklater plans on shooting Stephen Sondheim’s 1981 musical every couple of years for the next 20 years. One sequence that had already been filmed, the concluding number “Our Time,” had to be reshot following Paul Mescal replacing Blake Jenner in the cast. (Beanie Feldstein and Ben Platt are also in the cast.) That means we’re looking at a release for “Merrily We Roll Along” in the early 2040s.

“Merrily” famously tells its story in reverse-chronological order over 20 years, to show how movie producer Franklin Shepard (Mescal) abandons his friends as he moves through Hollywood. And as opposed to a conventional production in which makeup would age or de-age the actors during the course of a typically compressed film shoot, Linklater wants to capture the process of aging, the experience of time itself, in his film. That means many fans of the musical alive today will not make it to see the final product 20 years from now.

Linklater talked to IndieWire at the Texas Film Awards and addressed these concerns.

“What I do feel is when older people, pushing 80 perhaps, come up and say, ‘Oh, I hope I’m around when it comes out,’” Linklater said. “Someone on that age scale, you might look… I can see how the actuarial tables say you may or may not be around to experience the final movie. But frankly, I’m on that same table, so I tell them, ‘Don’t count yourself out.’ We’re all getting there.” The 62-year-old director will be in his early eighties when the film is released.

Does he see this filming process as being even more difficult than “Boyhood”? “On the one hand, yes,” Linklater said. “But they’re very different, just using the same longitudinal storytelling technique. They’re just such different stories. But also, ‘Boyhood’ was every year like a time-lapse, but ‘Merrily’ is like nine times shooting in 20 years, so there’s a two-year gap between each time shoot. Sometimes, two years in a row, but the schedule is all over the map.”

When Mescal’s casting was announced earlier this year, some, such as the author and film journalist Mark Harris, took to Twitter to advocate for a more conventional production that we could see sometime before the mid-21st century. “Great recasting, please just shoot the movie all at once, use makeup, it’ll work fine,” Harris wrote.

Linklater’s response to Harris? “He’s young enough to take the ride with me and everyone else.”

Whether it’s a holodeck on which we’re watching this then or some other yet-to-invented exhibition mechanism, time will tell.