Personally, I'm on the OP's train as well.
Kadri & Brown ($6.6m) are still over a $1m more expensive than Nylander + Brown replacement (~$800k, totaling $7.75m)
If you trade Nylander. It's become pretty obvious this year, that for the most part, the Leafs have not missed the real William Nylander -- both when he was in a holdout, and in his current level of play.
If you trade say, Nylander & Brown, you're still left with the following very impressive forward group for next year:
Hyman-Tavares-Marner
Johnsson-Matthews-Kapanen
Marleau-Kadri-_____
Moore-Gauthier-Petan
That amount of freed up cap space up front would likely give the Leafs the ability to go from 1 or 2 year deals on Kappy & Johnsson, to 3 or 4 year deals, and still leave enough space to bring on a defenceman like Brett Pesce, which they could easily do with Nylander on the table.
There's obviously a lot of doom & gloom about next year's cap for the Leafs, but I think if you subtract Gardiner, Nylander, Brown from this year's team, add Pesce, maybe a reclamation project RW (Jesse Puljujarvi?), and another year of development of Marner, Matthews, Johnsson, Kapanen and Dermott, I think that's a really solid foundation of a cup-contending team. Look to add a wayne simmonds-type around the deadline.