To CAR:
Jaroslav Halak ($4.5M - 17/18)
Matt Greene ($2.5M - 16/17)
From CAR:
Eddie Lack w/ 50% retention ($1.375M - 17/18)
To NYI:
2017 2nd LA
From NYI:
Jaroslav Halak ($4.5M - 17/18)
To LA:
Eddie Lack w/ 50% retention (1.375M - 17/18)
From LA:
Matt Greene ($2.5M - 16/17)
2017 2nd LA
Why Carolina does this: They upgrade there goaltending at the cost of short-term cap space. For a team with loads of space and goaltending holding them back, this should be a no-brainer.
Why New York does this: They end the 3-headed monster goaltending experiment finally and open up that roster spot. Also acquire a 2nd rounder (presumably for Snow to use to move up as always) and get rid of Halak's cap hit for next season, opening up money for Greiss, Clutterbuck, CDH, and potentially a FA or Seidenberg back.
Why Los Angeles does this: They need a goalie after all the injuries (and even before it, since I don't believe Zatkoff is NHL caliber) and Lack at 1.375 is a steal. Plus they get rid of Greene's cap for this season, potentially opening up space for a TDL acquisiton. The only cost is a 2nd.
And why does CAR want to add 14.75m in salary (in addition to retaining 2.75m on Lack) over the next 2 seasons? I mean this proposal certainly doesn't give them any incentive to do so. You say to "upgrade" their goaltending. If that's the case, why are they taking back Green? Green and Lack both make 2.5m, why wouldn't LA and CAR just flip those guys with someone (likely LA) adding, and then go shopping for a goalie?
Secondly, there's little chance NYI is going to move on from Halak during the season without taking salary back. Even if it's a team like CAR, they're going to want to move one of their two goalies (and not in a flawed proposal like what you listed).