Selected by the Maple Leafs with the No. 4 pick of the 2015 NHL Draft, Marner has 224 points (67 goals, 157 assists) in 241 regular-season games and 17 points (five goals, 12 assists) in 20 playoff games.
Dubas said he's had an ongoing dialogue with Marner's agent, Darren Ferris, and is open to any kind of contract.
"In a situation with a player like Mitch and what he means to our team not only on the ice but off, whether it's long term or short term we're open to discuss most of the available terms," Dubas said. "Whatever may feel right for Mitch in the areas that we're willing to discuss, we'll go down that path."
Dubas said his concern for an offer sheet has diminished because teams have come close to setting rosters for the season and there hasn't been many trade discussions.
"We've had a few calls, but it hasn't been ringing off the hook with teams either, I think because they feel we want to keep him," he said. "Not sure what they're hearing from the other side, but Mitch has said publicly this is where he wants to be. There haven't been that many discussions. I don't want to think about crossing that bridge."