I think your even overrating Calgary's desire to unload that contract. They brought him in a year ago, they knew what they were getting themselves into Edmonton retained 12.5%, and he had a good play-off. Not saying they'd be totally against it, but is it a high priority for them? I'm not so sure.
They might not be overly pleased with Hanifin's development, but they also have just 3 other D under contract for next year. Is shipping out Hanifin for another winger really something they'd be prioritizing?
Why are they retaining salary on either? Do they have a great need for more cap space this coming year? How much more do the Bruins have to give up to get some salary retention to make your Uber-D-Corps suggestion work in a cap system?
Well , you may be right but isn't if the other team is willing contingent to any proposal. Most of us don't get talk to any teams GM so ya, it's hypothetical . I have no idea if they want to unload Lucic's contract or not. I imagine no GM is enamored with any player taking up 5.25 cap space and producing a total of 20 points. I get that they only brought him in a year ago but that was to unload an equally bad contract so there is some evidence that they are not crazy about that kind of money not baring the fruits one would expect.
No team wants to retain money it's what they do to make a deal work for all.