Is there any precedent for a team taking back salary for that duration? I don't see it happening here.
I think it's a good fit for both teams and find it a fun exersize to try to make it work, but I think the path to getting there involves removing Mrazek -- they only need an extra $2M after that. They'll find someone who wants to play backup for cheap.
In other words, I think the bigger issue is that TOR doesn't have a whole lot to give up in a trade.
Leafs did it with Kessel... that deal did yield Kasperi Kapanen (highly regarded young prospect) and a 1st round pick (with the Leafs giving up some lesser assets as well in the deal.
Personally, I don't think the "challenge" with Gibson is whether he makes $6.4m or $5.0m. At the end of the day, that's #1 goalie money... and you can only have one #1 goalie -- it's not like a skater where you can turn a star on one team into depth on another.
The challenge is -- he's locked into being paid #1 goalie money for the next 5 years, but the last 3 has been very, very mediocre.
I think there's a bunch of teams (not good ones) that would happily take him on for the next 5 years at his full hit, simply to stabilize their goaltending with behind a likely young core, which gives him a really stable "floor" of positive value. However, given how mediocre he's been for the last few years, I'm not so sure there's a contending /good team that views him as the best way to spend $5-6m with term.
Look at the Freddy Andersen deal... and that was Carolina giving up nothing for him. Bad teams obviously wouldn't have access to a goalie contract like that, but at the same time, bad teams also generally do not want to give up a haul of futures.