No one, outside of maybe Shanahan and the MLSE board, knows exactly what Brad Treliving's gameplan to "fix" the Leafs is, but according to Elliotte Friedman, who spoke on Sportsnet last night, it does not involve moving the "Core 4".
Friedman said that he believes Treliving will do what Kyle Dubas did in recent years and change the pieces around the four Leaf forwards, but will focus more on the blueline. Treliving has a history of trading for and drafting defensemen, and the Leafs certainly need someone to play with Morgan Rielly and perhaps one more physical blueliner.
That may come as a surprise to many, given that Dubas said nothing was off the table during his season-ending press conference, but now Treliving needs to see what he has in the "Core 4" before making any major decisions regarding them. Friedman also reported that he believes all of Matthews, Marner and Nylander genuinely want to stay in Toronto which could have influenced Treliving's plan when in discussions with Shanahan about the job. If that is the case, then extensions for Matthews and Nylander should be easier to get done than first thought, but that does not mean they will sign July 1st. They may still want to see how Treliving builds the team around them before committing long-term.