Mutual rescission of a contract happens all the time.
I think the bigger question is what are the cap impacts of this? I don't know why all rich teams wouldn't do this to get rid of bad contracts if it just removed the hit. Give the guy a big enough payout and why should he care? Is that player forbidden from playing on another team until the years of his original contracts are done or something? This is like a free compliance buyout otherwise. Pay someone off, get rid of the cap hit, get rid of a contract. All you need is the money to do it.
Hypothetically, does that mean the Wings could pay Abdelkader $100m tomorrow to induce him to agree to terminate his existing contract?
That seems ridiculous.