If you are planning on taking equal money back for Marner your proposal may not work under the cap.I see it like this...
Re-sign Hyman to play with Matthews and find another more experienced, but cheaper setup guy to replace Marner. I like him, but his contract has got to go. Willy is cheaper, and locked up for longer, so makes better financial sense to keep him. If you don't like him next year, you can still move him before his NMC/NTC kicks in in a couple years.
Play Willy with Tavares and find a gritty winger to dig the puck out for them just like Hyman does now.
Keep Foligno and Spezza as your #3 and #4 centres.
Keep Kerfoot, Simmonds, and hope one or more of Robertson, Brooks, or Amirov can step up for the regular season. Maybe go shopping for another quality #3 or #4 winger.
Keep Muzzin, Holl, Brodie, Sandin, Dermott, Hutton, and Lilejegren. See how Bogosian looks early on in the reg season, upgrade if necessary.
Shop for a major stud on defense to replace Reilly.
Keep Campbell, Rittich. Shop for a better #2
This means trading Marner, Reilly, Mikheyev, and Engvall if possible.
Let go of Thornton, Nash, Galchenyuk, and Andersen. Maybe Andersen can be re-signed for less...if so, do it and send Rittich to the Marlies. If not no biggee IMO.
Basically, its add two quality wingers for what you were paying Marner; Get a quality 3rd line guy to upgrade bottom six. Add a stud defenseman with money from casting off Reilly, Andersen, Mik, Engvall, Thornton, Nash, and Gally.
Hyman is a big raise. Anderson going away offsets that.
Foligno only fit under the cap this year because Columbus retained and you only had him for 25% of the year. So it may have cost you about maybe $700k of cap hit In 2021 but next year it will be over 5 million.