The Calgary Flames won't be a playoff team during Markstrom's tenure
The Calgary Flames had their opportunity in the playoffs during Markstrom's run, but after the departure of Johnny Gaudreau and Matthew Tkachuk along with all the free agents this past year, they just aren't ready to compete for a playoff spot. With just two years left on his deal, the Flames timeline doesn't matchup with Markstrom, who would love to compete for a Stanley Cup at some point in his NHL career.
At 34-years of age, Markstrom is clearly ready to compete for the playoffs, and no matter what the Flames front office believes, this team simply isn't ready to make a substantial push. Sure, with or without Markstrom, they'll win some games and potentially be within striking distance with a few months to go in the season, but given the playoff hungry teams that need goaltending help, trading him is the obvious move to make.