They seem to want to re-tool.
They do not want Korpisalo. They want Chychrun. They do the goalie swap both to give Ottawa additional incentive to make the trade, but also to gain short-term cap and solve their problem with Markstrom wanting out and being difficult to move.
Markstrom wants out. He will be difficult to trade due to his up-and-down play, cap hit, and full-NTC. Markstrom has 12M over 2 years left on his contract after this season, he also has signing bonuses that make a buyout pointless.
Korpisalo has 20M left over 4 years after this season. Korpisalo does not have signing bonuses. If he doesn't bounce back with Calgary next year, a 2025 buyout saves them 3.66M of that 20M. So the swap in a worst case scenario would be very close to cap neutral for them. Then when you factor in that Chychrun is underpaid by a few million next season, and it's pretty much a wash cap wise. It just comes down to whether they value cap from 2024-2026 more than cap in 2026 and beyond, when Korpisalo would be on the books due to his additional term.
As I said in my original post, I suspect value wise that Chychrun is above Weegar. Weegar is signed well into his mid 30s and has a full NTC. Chychrun is 25 years old, and even an 8 year extension will mostly take up prime years. If Calgary is intent on re-tooling or re-building, either one, Chychrun is a much more dynamic asset than Weegar. They can audition him this season, and if he refuses to extend, they can flip him at the draft for a 1st+, or if he will extend with the team acquiring him, a massive haul. The trade market for Weegar is going to be much more limited than the market for Chychrun.
So in short, Markstrom for Korpisalo is a wash. They are both negative value assets. Cap wise, they are structured differently, and it comes down to whether Calgary values moving out a disgruntled player and gaining short term cap over long-term cap. Chychrun's cap savings compared to market value also factor into that equation. Then a Chychrun for Weegar swap gets them the more valuable and dynamic asset, whether to keep, or to trade.