According to Variety, the actor's seven-year run as erratic Dunder Mifflin boss Michael Scott will end, but Bromstad said the show will go on.
"We've been lucky to have had him as long as we've had. These things happen when you have such a major movie star in a show," she said.
"Not to diminish the departure of Steve, because that will impact the show, but we have tremendous faith in the writers and actors to keep it alive," Bromstad said.
In an affirmation of NBC's faith in a post-Carell, The Office, Bromstad said the sitcom will remain in its 9 p.m. EDT Thursday time slot.
Carell, 46, who's become a busy big-screen actor during his Office tenure, has said in interviews he plans to leave the series to better balance his work and family life. He's married with two children.
Whether Michael Scott's job will be filled by a promotion from within or an outside hire is under discussion. Bringing in a big-name star is an option, but "it's not the front-running idea," said Paul Lieberstein, a cast member and executive producer.
"It's not obvious to me we should stop," he said. "When Michael Jordan left the Bulls, nobody said the Bulls should stop. They didn't say, 'Shut down the franchise.'"