I wouldn't commit long term to him, but there's zero doubt he's been a major stabilizing force on the backend this season. With how good (especially for how young) the defence is this season, I wouldn't be opposed to keeping the unit together. Also with no real high priced defenceman, that means this team can invest more in keeping it's forwards together.
For me though, it comes down to two factors: 1) do they lose Davidson, and 2) how does Nurse preform down the stretch. If he continues to progress, he brings a lot of the same positives as Russell: good defencively, high end skating, and a willingness to go get in front of a train for the team.
Klefbom-Larsson
Sekera-Russell/Nurse
Nurse/Davidson-Benning
Reinhart, Oesterle, Fayne
I'm happy with that for next year