LOS ANGELES — For most of last week, movie theater executives clung grimly on.At issue, among other things, was CinemaCon, an annual Las Vegas event intended to bolster the most fragile part of the film business: leaving the house, buying a ticket and sitting in the dark with strangers to watch stories unfold on big screens. The National Association of Theater Owners was under pressure to call off the convention because of the coronavirus pandemic, but worries abounded about potential consumer fallout.What message would canceling the confab send to potential ticket buyers, including those increasingly likely to skip cinemas — even in the best of times — and watch films on streaming services like Netflix, Amazon Prime Video and Disney Plus? American cinemas, after all, were staying open in the face of the pandemic.Reality eventually made the association pull the plug on CinemaCon, another example of how seemingly every part of American life has been disrupted because of the coronavirus. For movie theaters, however, the pandemic could be a point of no return.The National Association of Theater Owners has insisted that streaming services are not a threat. “Through every challenge, through every new technology innovation over the last twenty years, theatrical admissions have been stable and box office has consistently grown,” John Fithian, the association’s chief executive, said in a January news release titled “theater owners celebrate a robust 2019 box office.” Ticket sales in North America totaled $11.4 billion, down 4 percent from a record-setting 2018.Many analysts, however, see a very different picture. Looking at the last 20 years of attendance figures, the number of tickets sold in North America peaked in 2002, when cinemas sold about 1.6 billion. In 2019, attendance totaled roughly 1.2 billion, a 25 percent drop — even as the population of the United States increased roughly 15 percent. Cinemas have kept ticket revenue high by raising prices, but studio executives say there is limited room for continued escalation. Offerings in theaters may also grow more constrained. Even before the pandemic, major studios were starting to route smaller dramas and comedies toward streaming services instead of theaters.And now comes the coronavirus, which has prompted people to bivouac in their homes, theaters to put in place social-distancing restrictions and studios to postpone most theatrical releases through the end of April. Rich Greenfield, a founder of the LightShed Partners media research firm, predicted that the disruption would speed the ascendance of streaming.“The behavior was already shifting, but this hits the accelerator pedal,” Mr. Greenfield said. “I think most of the global exhibition business will be in bankruptcy by the end of the year.”He added, “Now studios are going to think more and more about why they are relying on third parties to distribute their content.”As studios have postponed theatrical releases like “Mulan” and “No Time to Die,” they have been careful to express loyalty for theaters. “We believe in and support the theatrical experience,” Paramount Pictures said in a statement on Thursday, when it announced that “A Quiet Place Part II” would no longer arrive in theaters on March 20. But a question looms: Could the pandemic hasten long-brewing changes in the way that new movies roll out?Most movies still arrive the same way they have for decades. They appear first in theaters, for an exclusive run of about 90 days, and then in homes. Theater chains, including AMC, Regal and Cinemark, have fought off efforts to shorten the exclusivity period. They worry that people will be reluctant to buy tickets if they can see the same film on their living room television set or iPad screen just a few weeks (or days) later. More