I don't know how likely this is, but the best thing that could happen now would be for Mitch to sign an eight-year extension for $80M.
If he is wants to be a Leaf (and therefore would waive his NMC) then he can show that for signing up long term for less than he was making before. We give him fill NMC again and if he continues to under deliver come playoffs then we try to trade him in the future. He has more value locked in at that number and he gets to pick his spot. It could be a win/win for this situation, possibly the only one. I don't like the idea of him walking for nothing or playing for a contract this year.
Also, JT should signed a four year extension at $3M per year. He should also offer to give up his C for Matthews (or trade it for an A).
We want a culture change? New GM (last year), new Coach, new Captain, players taking less to be Leafs (or remain Leafs), re-built D, a wave of young players stepping in and contributing on ELCs or second deals, and $9M more to spend next year just because MM and JT took less.
This all starts with Marner being an easy re-sign a year early.