Gibson is just so tough to move with that contract. There's a ton of expensive risk involved. Not sure there's much that would make sense, other than some sort of swap for a different expensive goalie...and just hope and pray he bounces back in a different, better defensive situation. He still sort of passes the eye test, but it seems like with age, he's been exposed particularly by the sort of chances that Anaheim bleeds in front of him. On a team that can protect against second chances, corral rebounds he might let out, cut down on cross crease tap-in type puck movement...i could see him still playing at a reasonably high level. But that stuff that has dropped off in his game seems exacerbated by the Ducks defence lacking the ability to stymie those sorts of opportunities.
Which leads to Fowler...who would honestly be a great pickup for a team that can slot him in more appropriately as a sort of #3D, rather than just being the guy who gets sent out there as a bit of a martyr, to get caved in with tough matchups and huge minutes. He's still a good, mobile, puck moving D who could easily handle secondary matchups, especially with a solid reliable partner. I think his contract is a lot easier to move too. $6M is not bad for a Top-3D in today's market. As long as he's willing to go to pretty much any team that'd want him (mostly just going to be playoff or at least bubble teams), i think he's plenty moveable, and for value even. Though naturally, with that kind of $$$ moving, there'd probably have to be a "cap offset" coming back the other way. Most teams that would be in on him are pretty tight to the cap.
I'd happily take Fowler on the Canucks. Add some more mobility and puck-moving ability outside of Hughes-Hronek. Anchor a 2nd pairing. But i'm not really sure there's anything realistic that would make the cap work there...short of max retention for the remainder of the deal, which i'm not sure the Ducks would be that interested in.