If he's traded and doesn't report, the team that acquired him could terminate his contract.
If he and his agent influence the process so that no one wants to trade for him, the Rangers can't terminate his contract. They could try, and if by some bizarre turn of events the league permitted it, it would be a grievance that would go to arbitration. And the Rangers would likely lose, and either have to reinstate him and pay him his money or settle with him--something similar to Corey Perry.
No one is going to be trying to terminate his contract, basically. Not some other team, because they won't acquire him unless they know he'd report, and not the Rangers, because they don't have any grounds to do so.