The Miami Herald's Barry Jackson reported the Marlins have discussed offering Realmuto a contract extension and that it would take "an astronomical offer" before the team would weigh a trade.
The Marlins have plenty of time before they need to offer Realmuto a contract. He's eligible for arbitration in 2019 and 2020 and will become an unrestricted free agent in 2021.
The fact that the Marlins would consider an extension for Realmuto is somewhat surprising given his age. He turned 27 in March, so he's in the middle of his prime. By the time he's eligible for free agency, he'll be approaching 30.
Miami traded Dee Gordon, Christian Yelich, Marcell Ozuna and Giancarlo Stanton in the offseason, kicking off a substantial rebuild. By the time the team's in a position to contend again, Realmuto could be on the wrong side of the aging curve.
By re-signing Realmuto, ownership would be showing it's done cutting costs. But Realmuto arguably has more value to the Marlins as a trade asset given their state.