Let Marner walk. Bring back Tavares short term for hopefully a good discount. Go long term with Knies. Don't need to be painted into a corner having to pay him 12 million 3 years from now after a bridge. Get it done 8x8 now if you can. See if you can get a reasonably good deal in the high end FA market with someone like Ehlers or Boeser, if not go short term and hope McDavid is an option next offseason. If that fails we trade off Matthews summer of 27 and go full rebuild when we finally have our 1st rounders again.
Not a fan of moving on from Rielly yet. I get that he didn't play all that well this past year and could be in a decline but has been one of the few guys who steps up in the playoffs with production. He's the only real offense first guy we have on a backend that IMO struggled to consistently move the puck out of the D zone with possession in the Florida series, and often failed to exit the zone altogether. Tanev, McCabe, Carlo, OEL just isn't enough puck moving capability from the backend and it's going to lead to continued problems with controlled breakouts under pressure. I fail to see how you're going to do much better for the 7.5 million to replace him in a FA world with a huge cap jump.
Most importantly don't trade another 1st rounder again unless you're getting a huge upgrade. They McCabe and Carlo trades were reasonable because we got a couple longer term pieces we needed but we've wasted a ton of 1sts on some really useless assets over the years. Dallas didn't get where they are by trading all their picks. Instead they used mid/late 1st rounders on Johnston, Harley, Bourque and Bichsel while making some solid 2nd round picks in Hintz and Stankoven. It allowed them to continue to compete while their expensive core of Benn and Seguin aged and now that Benn's expiring they were able to finally move a couple picks and Stankoven for a legit star in Rantanen and extend him. Sure would be nice to have done it their way.