My prediction for the following offseason for the leafs.
I think Matthews will sign for cheaper than most think, as he is currently after a 5 year deal and thats not where RFA's make their big money. If Matthews was reaching for a contract in the 11.5-12.5/ year range, he would have to let the leafs buy out more of his UFA years. If he is intending on using McDavid as a comparable, then AM will likely have to request the term to match (8 years).
Marner will have trouble asking for more than 9 in RFA negotiations, as there are no comparable players with contracts of that magnitude leaving their ELC. If Marner is reaching, his agent will ask for Kucherov money (who is moving on to his 3rd contract, so not a real comparable) but is making 9.5/ season. Marner is not Kucherov, and if he wants to prove he can be he will have to take a bridge to put up that production. (which will never be desired by MM's camp or Dubas).
Kapanen and Johnsson, Bridge deals, try and prove their worth. Kapanen I could see getting closer to 3m for 2 or 3 years.
With Muzzin now here, it is a foregone conclusion that Gardiner is gone, if it wasn't already. Muzzins arrival will likely lead to the departure of a player or 2. On the list of possibilities includes Kapanen and Johnsson, which I think is undesirable by leafs management.
Then it includes Nylander and Zaitsev entirely due to their contracts. Nylander would be an idiotic trade as he has proven over the past 3 years the player he can be. He is underperforming and his value will be at an all time low. Dubas also promised him he would not trade him. Zaitsev may get the brunt of the complaints from Leafs fans and media, but really name an established Dman on the leafs in the past 10 years not name Morgan Rielly who hasn't gotten heavily criticized. Zaitsev is a very serviceable defencive d-man who would slot in perfectly as a top 4 guy on almost any team. Getting rid of him because he might be paid 500-750k too much would just create another hole.
Lastly, the more possible options are Hyman and Brown both getting over $2m a year with little production. This year has shown how much Babcock likes and trusts Hyman as a role player. Brown has spent most of his time in the bottom 6 and will likely be moved for cap relief in my opinion.
Following this season, with the cap likely going up another ~3mil, and Marleau being off the books the leafs will alleviate some pressure. Liljegren, Sandin, Bracco, and Rosen should all be pushing for spots in the NHL lineup by the 2020-21 season and the serious contract will already be sorted.
The cap situation will not be easy to navigate, but IMO it can be done without compromising the Top 6 or the top 4 at all (aside from the loss of Gardiner), and still have a very serviceable bottom half of the team.
I could, and am likely very wrong with all of this. I made this more to figure it out for myself, and wrote the description to process my thoughts.