I'm thinking it's kind of a group of 11D who will be competing for a spot.
Skjei, Shattenkirk, Staal, Smith, ADA, Pionk, Claesson, Kampfer, O'Gara, Gilmour, Bigas
Out of those Pionk, Gilmour, O'Gara are waiver exempt. Whether we like it or not waivers are something a team has to factor in.
Similarly not letting developing players become the default scratch is another factor.
They likely will hope some of the vet NHLers can increase their trade value even if that may be far fetched.
I assume they keep 8 defenders on the NHL roster. Until camp/preseason I don't think any of them are locks except Skjei, Shattenkirk.
Not including injury or a trade
I assume if Smith and Staal are viable they stay up
I don't think they are going to waive ADA and they will want to see Pionk at the NHL level again.
I think Claesson, Kampfer are the players they are not thinking it hurts them to be scratches
Bigas is waiver eligible, if he plays well enough I'm not sure if they take that chance, I assume they would rather risk Kampfer to waivers but it will depend on the play of Bigas and if they think he will just be scratched anyway.
Gilmour, O'Gara are waiver exempt, I think they'd really have to wow them or have someone else really disappoint to make it, but if either or both does impress enough I assume it is somewhat possible they bump Claesson, Kampfer, maybe even Staal, Smith, or even Pionk out but I think that is a sort of a remote possibility, and again if they are only going to end up the scratches it's not really helping them improve.