There is one method still available to "weaponize" cap space - when a team really needs to move some salary in order to make a bigger deal - similar to how Mike Gillis got Christian Ehrhoff out of San Jose.
Clearly Dallas and Tampa are both negotiating to get Erik Karlsson from the Senators. The ask for Karlsson has to be huge - I would guess a top tier prospect, a 1st round pick and another useful asset or two. As Eugene Melnyk is cheap, he also doesn't want to take back salary and Pierre Dorian - faced with trading the face of the franchise is looking to hit a home run - and replace the 1st round pick they gave to Colorado in the Duchene deal.
So ...
Ottawa:
- OUT: Erik Karlsson, 2019 3rd round pick
- IN: Miro Heiskanen, Dallas 2019 1st round pick, Ben Hutton, Brendan Gaunce
Dallas:
- OUT: Miro Heiskanen, Julius Honka, 2019 1st round pick and Jason Spezza (cap dump)
- IN: Erik Karlsson
Vancouver:
- OUT: Ben Hutton, Brendan Gaunce
- IN: Julius Honka, Jason Spezza, Ottawa 2019 3rd round pick
Ottawa hits the home run - they get one of the best 3 or 4 defensemen under 20 in the world, a first round pick and a roster player in Ben Hutton who can step in today on their (depleted) defense.
Dallas gets one of the top 3 defensemen in the world period. They also offload Jason Spezza's contract on Vancouver while giving up another young defender who has potential but has been inconsistent. They basically give up the long term future of the present, but they will be in cap trouble in the near future.
Vancouver basically swaps Ben Hutton (an inconsistent 25 year old puck mover) for Julius Honka (an inconsistent 22 year old puck mover with higher potential) and Brendan Gaunce for Jason Spezza while picking up a 3rd round pick.