"I think he will definitely be wearing a different uniform by the start of spring training," Berry said, according to Jon Morosi of MLB Network.
The 27-year-old is eligible for arbitration and isn't scheduled to hit free agency until 2021 barring an extension, which Berry made clear wouldn't be signed with the Marlins.
"J.T., you know, he's informed the Marlins ownership, he's informed their front office he's not going to sign an extension in Miami," Berry said. "From that standpoint, you could keep him for two years, or not. And it makes sense when you have one of the more valuable trade assets in baseball to move him. Period."
Miami entered a rebuild after the 2017 season and traded away a number of high-profile players. Giancarlo Stanton, Christian Yelich, Marcell Ozuna, and Dee Gordon were each moved over the last offseason while first baseman Justin Bour was dealt during the campaign.
Despite missing time at the beginning of the regular season, Realmuto was productive at the plate and is one of the best offensive catchers in the game. He hit .277/.340/.484 with 21 home runs and 74 RBIs in 125 games while being named to the All-Star team for the first time.