As a result, Streit will hit the open market July 5 as an unrestricted free agent and is looking to get a deal worth more than $5.5 million per year.
Newsday suggests Streit could receive a four-year deal worth around $6 million per year on the open market, as there aren't too many top-tier defensemen available this summer.
Streit, named captain prior to the 2011-12 season, is in the final year of a five-year, $20.5 million deal he signed in July of 2008.
In 48 games with the Isles this season, the 35-year-old Streit collected six goals and 21 assists for 27 points.
The native of Bern, Switzerland has played in 491 career NHL regular-season games with the Montreal Canadiens and Islanders, and has accumulated 65 goals and 223 assists for 288 points.
Meanwhile, Newsday also reports forward Brad Boyes won't be back with the club next season, either.
Boyes, who tallied 10 goals and 25 assists for 35 points in 48 games this season, is also set to become a UFA this summer. Talks between his camp and the Isles will continue through July 5, but it's believed he'll test the market.