The director has not directed a feature since 2006's Inland Empire, in which Dern starred as an actress who loses her mind in the course of seeking a comeback role.
"I will be working with David Lynch when I'm 80," Dern promised. "He is cooking, he's cooking up trouble, and I will be part of that trouble.
"He's the consummate renaissance man, he just makes art wherever he can get his hands on it. But film, ultimately, I know is his great love, and I think he will always circle back to it. He's definitely cooking."
In recent years Lynch has embraced the internet as a mode of distribution, producing a series of short films including 2002's Rabbits and DumbLand.
"Even if I had a big idea, the world is different now," Lynch said of his future as a director last year.