You can sign a left defenseman who may not be Marcus Pettersson, but can insulate Karlsson and be the safety net that he needs. Karlsson isn't the only player in the NHL that needs a defensive conscience as a partner. This happens all the time with a bunch of different offensive defensemen. I think Adam Fox was at his best when Ryan Lindgren was playing at his best. Can we find someone who can be for Karlsson what Brayden McNabb is for Shea Theodore?
We can try someone like Derek Forbort, who I don't think would sign for crazy money. Or we can go higher and take a shot at one of the big three Russian UFA D-men (Orlov; Gavrikov; Provorov). Or maybe give Lindgren a shot. Again, it would have to be relatively cheap, not an overpay. The Russians, I would be OK with overpayment.
Promote Pickering. Sign one of the aforementioned LD. Keep Timmins if he is cheap to play the third pairing. Keep Kolyachonok because he is cheap, young and filled with some untapped upside. Let Grz go. Shea, whatever. His contract is cheap enough that you don't need to bury any salary if you waive/send him down. He is a No. 8, ideally.
And if Timmins' qualifying offer is too much, then do not qualify him and try to bring him back more cheaply. If that does not work, give Brunicke a legit chance.
Forbort-Karlsson
Pickering-Letang
Kolyachonok-Timmins (or Brunicke)
Graves
Shea (safety net)
This blueline is not great, but we have a systemic issue with the team defense that will not be cured by personnel changes alone. But Grzelcyk's absolute best season is still not as good as Karlsson's (arguably) worst. AND, Karlsson cannot play worse than this, while Grzelcyk is absolutely not going to do this ever again.
It's a no-brainer to keep Karlsson and let Grz go. Which is why this organization will do the opposite, because they have been making wrong decisions since 2018.