"The door will always be open for Marshawn," Gruden told reporters at the NFL Coaches Breakfast.
That door could remain ajar until deep into April.
"We have a big question at running back," Raiders general manager Mike Mayock said Monday, per The Athletic. "Both parties have to wait for the draft and see what happens there."
Lynch, who has not committed to playing in 2019, is currently a free agent. The 32-year-old bruiser came out of his one-year retirement in 2017 to play for the Raiders in his hometown of Oakland.
In two seasons with the club, Lynch totaled 1,502 scrimmage yards and 10 touchdowns on 332 touches. Beast Mode missed 10 games last season with a groin injury.
With the team's residence status up in the air as the 2018 season closed, it was unclear Lynch would return to the club or football entirely. In other words, if the Raiders moved out of Oakland, Beast Mode wouldn't go with them.
But the Raiders have now been approved by the Coliseum Authority, the city of Oakland and the NFL to remain in the Coliseum on a one-year lease in 2019 with an option for 2020.