LOS ANGELES — The final installment of “The Hobbit” doesn’t just mark the conclusion of Bilbo Baggins’ journey on the big screen. It’s also the end of a massively successful film franchise that’s earned New Line and Warner Bros. nearly $5 billion, going all the way back to the 2001 release of “The Lord of the Rings: The Fellowship of the Ring.”

“I don’t know what to compare it to because I’ve never been involved in a project that’s gone on for so long or been such a huge success,” said Toby Emmerich, president and CEO of New Line, the unit of Warner Bros. responsible for releasing “The Hobbit” and “The Lord of the Rings” films over the past 13 years.

The marketing campaign for “The Hobbit: The Battle of the Five Armies” promises moviegoers “one last” trip to Middle-earth. Will it really be the final outing for all those dwarfs, elves, hobbits and orcs? After all, “The Hobbit” was originally envisioned as two, not three films.

“I wish I could say differently,” said Emmerich. “There is nothing at New Line or Warner Bros. I think there could be another video game, and Middle-earth will probably live on in licensing and merchandising a while longer, but we do not have any plans, as far as I know, to tackle another Middle-earth movie.”

“The Hobbit” and “The Lord of the Rings” filmmaker Peter Jackson, who crafted all six of the films in his native New Zealand, was similarly adamant he was finished adapting J.R.R. Tolkien, though he would “never say never” to a Middle-earth homecoming.

“If we wanted to — and I don’t know whether I would want to or not — it’s not a question I need to worry about,” Jackson said. “Warner Bros. has the rights to ‘The Lord of the Rings’ and ‘The Hobbit,’ and they don’t have the rights to anything else.”

The fate of Middle-earth continuing in other realms beyond literature could be decided in a courtroom. The Tolkien estate and Warner Bros., which doesn’t have permission to adapt Tolkien’s later work “The Silmarillion,” have been legally sparring since 2012 over exactly what the studio’s film rights entail when it comes to merchandising.

“The Tolkien estate is very protective, as they should be, and I don’t begrudge them that at all,” said Jackson, who has expressed interest in creating a “Lord of the Rings” museum in New Zealand.

Is it possible New Line could take a cue from the producers of the James Bond film series, or from their very own colleagues at Warner Bros. Interactive Entertainment, and use Tolkien’s fantasy world as a backdrop for new stories? It recently proved both critically and financially successful for the video-game division.