The 83 year old admits he's often asked about calling it a day but he's not ready to "wipe the drool yet".
He tells Entertainment Weekly, "When I finished Lonesome Dove I said, 'I feel like I can retire'. That role was my Hamlet. But that was a long time ago.
"Terry Gilliam came to my farm, and he wants me to play Don Quixote in a movie. Men on horses, saving women... Maybe that will be my swan song, my exit part."
The film is Monty Python star Gilliam's latest attempt to get his doomed The Man Who Killed Don Quixote off the ground. Jean Rochefort was originally cast as Quixote in a disaster-ridden project, which served as the plot for 2002 documentary Lost in La Mancha.