Without reading the entire thread, here's my thoughts.
I'm going to give Treliving a chance to rework this team. May not happen after 1 season, so next season might not be some kind of game changer.
As to the core four, specifically Matthews. If he wants to stay here, it can't be at the max cap hit, around $14.6M i think. That would further handcuff this team, as it has been for the past few years because of the flat cap.
Yes, the cap is going up after this next season, but still. Yes, he deserves a raise, but it shouldn't be more than $13-13.25M.
And I think Marner will proably have to be traded to make room for that, and to give Willie a bit of a raise, and have some money left over to fill voids with decent players, not scrubs.