If I'm the Leafs, I'm trading Johnsson before I trade away Kapanen. There's two reasons for this:
The Leafs can ill-afford to make those kind of commitments knowing their core players need to be signed. Johnsson is a role player, but a very good one and will be a better one going forward. But when you look at Kapanen's body of work, his growth, development curve, etc., there's a potential for him to go from a role player to a core one.
I see a lot of mini-Hossa in Kapanen. I think it's imperative that the Leafs do everything they can to make Kapanen a priority after signing Matthews and Marner.
So to that end, if the Blues are interested in trading Pietrangelo to Toronto, I hope it's Johnsson going the other way.
And finally, I love that Dubas isn't fazed by the toughness factor. He's doing it right and hopefully sooner rather than later, people come around and realize he's doing the right thing for the franchise.