I'm 100% onboard with trading Mitch. However, you can't do it recklessly. Trading Marner for Jones would be a Hall for Larsson level disaster move (even if you attach a 2nd to Jones). Frankly, any satisfactory move involving Marner would be a soft reset kinda move, where you acquire a couple of highly regarded young players breaking into/about to break into the league to fit the window and even take on a short term 1-2yr overpayment ($6-7M total) to increase your haul. Then you'd grow these players alongside Sandin and Robertson to kinda be the new core pieces surrounding the other core three (like WSH did, moving on from Semin/Green as core pieces and transitioning to Kuznetsov/Carlson). It would be a statement move to send a message and it would serve as a good way to pivot to another philosophy because the one we have currently tried hasn't worked.
Think of something like the Jeff Carter trade from Philly to CBJ.