As far as a trade goes, any trade involving Klingberg (if management sees the writing on the wall) should involve a young righty defenseman, unless the prospect or pick offered up is significant. Dallas would only have Hakanpaa on the right side that is a true righty (Heiskanen plays on the offhand).
Teams that should consider Klingberg would be teams that need a boost on the PP that are playoff bound.
I like Carolina as a trade partner, but I don't know if they NEED him, unless Bear were to go the other way. Slavin-Klingberg would probably be a top 5 pairing in the league. But do they need him with DeAngelo? If they go all in though, a deal around Bear, a 1st, and a second tier prospect or Bear a 2nd and 1st tier prospect makes some sense.
Toronto makes sense, they could use a righty in their top 4. But would they be willing to give up a prospect like Robertson (yes please), Sandin, or Liljegren? Do they even have the cap space?
Washington could use PP help. Can't believe I'm saying that. But do they have the prospects to pull off a deal? Not sure.
LA could make sense, but they would be better off pursuing Chychrun.
Calgary might make sense, but they have predominantly forward prospects like Zary, Corronato, etc. Not sure if that makes sense for Dallas, or if Calgary would even consider that.
Florida is the only other team I could think of. Outside of the obvious prospects or young players, a guy like Benning could be a nice piece, Nause too. Not sure who's untouchable down there for a rental.
Overall, Klinger makes any team's PP better. I'm just not sure who is available from a prospect/player perspective that helps Dallas' right side long term. They have Heiskanen signed long term (thank the Hockey Gods for that), Harley, and Grushnikov in their system are the future. Suter and Lindell are both around for the next 3 years. All of them are lefties.