I know it's been mentioned before, but I think people are sleeping on the likelihood of the Senators as a landing spot for DZ.
Their D right now is basically Karlsson and a whole lot of size. And during the Sens-Avs game the announcers repeatedly mentioned the organizations desire to get more offense out of their D. There were also several reports of the Sens having interest in DZ earlier in the year.
Plus, it's not like the Rangers PP is exactly struggling right now... With the team likely hoping Allen makes the squad next year, Stralman unlikely to price himself out of resigning in NY, and McDonagh's continued improvement on offense, I don't think the Rangers are necessarily looking to replace DZ with a similar style of player. They already have that, kind of, in John Moore.
Hopefully the Rangers can pry some of that young size out of Ottawa, getting a little more size and snarl on the backend, while letting Moore play with a more defensively responsible partner, plus building a bit of defensive depth should the team decide to move/lose Girardi or even Staal at some point in the near future.