It is a lateral move. We gain points but lose ~5mil in salary and get a headache to deal with. There's a near zero chance MTL moves Dach in a trade for Dubois, it just doesn't make sense for the team.
Fantasize as much as you want about whatever leverage/pressure/gun-to-the-head Chevy has with a player holding out and dictating who he gets traded to, but it really doesn't make any sense. MTL/Hughes has a long term plan and vision for the team that likely doesn't involve sacrificing key building blocks for Dubois. As far as I can tell, MTL is in a position to comfortably walk away from a deal that doesn't suit them, WPG loses an asset/value of an asset the longer they wait.