Ask Marner to waive his NMC. If he says yes trade him to Nashville for Askarov, a first round pick and salary to make the upcoming extension for Marner more palatable. If he refuses to waive, force him to by telling him he's not being re-signed, is being stripped of his "A", etc.
Do the same for Tavares, if he won't waive, strip the captaincy and give it to Matthews.
Fire the entire coaching staff and throw money at Rod Brind'Amour. If you can't get him to come over, hire Berube instead.
Trade the Nashville first rounder, Robertson and Jarnkrok for another top six forward who can score goals.
Draft the highest upside player available with our own first. I'm thinking one of Connelly if he falls, Hage or Mews.
Trade Ryan Reaves for whatever you can get to clear cap space.
Let Brodie, Gio, Samsonov etc. walk and sign Matt Roy in UFA, use any cap left over from potential Marner/Tavares trades to chase Sam Reinhart and Brett Pesce.
Re-Sign Domi and let Bertuzzi walk.
Ideally your roster looks something like this:
Domi-Matthews-Nylander
Knies-Reinhart-Trade acquisition
McMann-Minten-Grebenkin
Cowan-Kampf-Tverberg (fourth line with defensive acumen, speed and potential depth scoring).
Rielly-Roy
McCabe-Pesce
Benoit-Liljegren
Timmins
Askarov/Woll Tandem