His total salary for each of the next two years is 4M, 8M in total remaining. And the way his deal is structured with signing bonuses, a buyout next year would hurt a lot. His contract is awful anyway you slice it.
CapFriendly - JOHNNY BOYCHUK
Johnny Boychuk - CapFriendly - NHL Salary Caps
To me he's essentially a replacement level player at this point, one of those guys you can easily sign for close to league minimum. Maybe his reputation and past abilities will trick some dumb GM into trading for him without much sweetener from the Islanders but teams should stay away.