Kevin Costner’s “Horizon: An American Saga” was conceived as a four-part Western epic, a decade-long passion project meant to play out like a grand, old-school saga. But after the disappointing box office performance of “Chapter 1,” the future of the entire series is now in doubt.

Sam Worthington, who had a major role in the project, revealed this week that the continuation of the saga may rest entirely on whether “Chapter 1” finds a large enough audience on streaming (via Variety).

“That was Costner’s passion project — he’d been working on it for 10 years,” Worthington said. “It all comes down to whether the audience connects. The passion is always there, but sometimes it’s just about whether it’s the right time for people to embrace it.” Worthington also confirmed that Costner had mapped out and written all four films, and that he’s read every script.

It’s a bizarre situation: a movie that flopped theatrically but went on to become the #1 most-watched title across streaming in January. “Chapter 2” was already shot two years ago but remains unreleased, while financing for “Chapters 3” and “4” has dried up. Costner even managed to shoot nine days’ worth of footage for “Chapter 3” before production was forced to shut down due to lack of funds.

Back in July, I reported that Netflix had made an offer to Costner, with the streamer interested in helping fund “Chapters 3” and “4” as part of a push to get into the Yellowstone/Western game. Costner originally declined, but given the lack of financing and a theatrical distributor, it wouldn’t be surprising if he’s reconsidering.

“Chapter 2,” which cost $110M, was pulled from Warner Bros.’ schedule last year. It eventually world premiered at the Venice Film Festival in September, where it drew weak reviews — further complicating distribution.

With theaters unlikely to be a viable path forward, Netflix is now the only (and smartest) option left for Costner to complete his saga. Just do it, Kevin.