Quoting: Barbs
I'm going to defer to the Ducks fan on this one. Aside from a team that's had their D completely gutted (like Winnipeg) I don't think there's much interest in Ristolainen. He's basically Cody Ceci but can score on the powerplay (but that might just be because of the supporting cast)
I know that Kase is likely Anaheim's best forward so I think the cost would be pretty high to acquire him
The only guy I can see Anaheim trading Kase for is Brett Pesce (and Carolina needs a top-flight right-handed forward), but I can't see the Hurricanes letting go of Pesce. Maybe Ryan Pulock on the Island.
Anaheim might deal from extra strength at LD (Guhle, Larsson, Mahura) or RW (Sherwood, Sprong, Terry), but I don't think that the Ducks would be willing to go higher on the depth chart right now. Management really wants to find out how the youngsters are developing while keeping the first-line core (Rakell, Kase, Silfverberg, Steel, Lundestrom, Comtois, Fowler, Lindholm, Manson, Gibson) intact. I think that the Ducks would also wait a year (or at least until the trade deadline) to trade good depth players like Henrique, Ritchie, Shore, Grant and Rowney.