I think Leddy would be a pretty good fit with Winnipeg. Their D is their weakest spot, especially on the left side. Myers was a disaster there, Kulikov is barely a 3rd pairing talent.
Winnipeg is set on the top pairing, so Leddy's responsibilities will be decreased. He helps now, but he also provides some depth in D as Winnipeg will likely have a difficult decision this summer with Trouba. So still having Morrissey, Buff and Leddy under contract will make it a little easier to deal with if Trouba ends up forcing his way out.
I would think a return around mainly picks or prospects like Petan and picks or something like that would make sense. If the Islanders would take the end of Kulikov's contract, they can probably squeeze even more value out.