Meh, I disagree with most of that.
Zaitsev: He's is not unmovable. They may need to make it worth someone's while, but he's not unmovable. Down the stretch and in the playoffs, he played quite well. He's a bit overpaid, but he has value IMO. In fact, I doubt the Leafs move him unless they can find another RHD.
Nylander: His value hasn't dropped as much as people let on. 1 bad year when he missed all of training camp and 1/3rd of the season isn't going to change that he's a young, skilled 60point players. GMs see that. His cap hit is certainly higher than it was, but after 7/1, his salary isn't bad. If the Leafs want to move him, there will be a lot of takers.
AJ: Not in the same position as Kap, as he's arb. eligible, but he's going to cost probably $2.5M so if the Leafs want to save that space, they can move him easily, which is my point.
Kadri: Another guy that can be moved to free up space if they need to. Gardiner won't likely be re-signed either.
My point being is that I highly doubt the Leafs would trade Kapanen for a 2nd round pick or refuse to match an offersheet that requires only a 2nd round pick (and remember, Kapanen has to agree to sign an offersheet). People fail to recognize that there are 29 teams in the NHL and many of them would want a guy like Kapanen. Leafs have a number of different things they can put in play vs. just taking a poor offer for wone of their players.