He could retire. It could become messy to the point where Stamkos leaves. Fans love him and he'd create a rift between management and the fans.
Florida isn't a hockey state. They struggle with revenue. St. Louis brings a lot of fans to the stadium. He has for years. They buy his jersey. They support his charitable programs and events. A rift between the two parties will alienate fans in one of two directions. 1) To resent St. Louis, leading to less positive sentiment for the team and less revenue that he brings by having die hard fans support the team because of him. or 2) resent the management for disrespecting him and forcing him to this situation.
In the process, it will distract the locker room, will undermine the new rookie coach's pull over the group they have in there (especially younger players), and will set a bad precedent and image to how TB management deals with their own players. Yzerman didn't take care of his own in the Olympics. He kept Kunitz and Crosby together. He kept Sharp with Toews. But he didn't keep Stamkos and MSL. Player's egos get in the way. It's an unfortunate reality. Some don't take it to heart, some do. MSL clearly did.
He's 38, in all probability he had more availability to talk to SY about his desire to represent Canada before he retired. Yzerman didn't listen. Now this.
Now he can get vocal and disrupt the best Tampa team to play since '04. Again, likely to the Rangers, for an even lesser return than our current captain.
Or Yzerman can get our captain in an attempt to salvage their playoff hopes for this season and maybe even be able to resign him too.
Makes a lot of sense to me.