How can the NY Islanders make a trade for Alex DeBrincat fit under the salary cap?

Alex DeBrincat's Next Contract

DeBrincat is currently a restricted free agent. He isn't currently signed to a contract, but the Senators are the only team that can negotiate with him - although he (through his agent) has been given permission to discuss contract terms with other teams. In other words, whoever trades for him will have already agreed to a contract with him. This makes him essentially the same as an unrestricted free agent, except that teams have to agree to a trade with Ottawa before they can sign him.

"DeBrincat's agent has been given permission to discuss terms with some teams. Has found out he can't get the kind of term that Ottawa is offering. The club has been close on some deals but haven't been able to close the trade because of DeBrincat's demand for more term."

Senators reporter Bruce Garrioch

The Senators have elected for salary arbitration with DeBrincat. It is unusual for teams to choose salary arbitration (the arbitration process is usually initiated by the player, not the team) but it is possible. However, salary arbitrators are only allowed to award a contract of either one or two years

It's not entirely clear what DeBrincat actually wants - He seems to be looking for a long-term contract, but not in Ottawa, and is otherwise content with becoming an unrestricted free agent in a year or two. However, Ottawa seems to be the only team that's offered him the type of term he's looking for to sign elsewhere.

"There's varying degrees of interest. Teams call, we get close to a deal, I give them permission [to speak to DeBrincat] and sometimes they're not ready to pay maybe the term that we're ready to pay."

Senators GM Pierre Dorion

There are essentially three ways this might play out. (1) DeBrincat could decide to accept Ottawa's long-term offer (we don't know how much money was offered). (2) He could change his mind and agree to a short-term deal with Ottawa or another team. (3) Another team could decide to offer him a similar term - and that's where the Islanders come in.