I'm probably in the minority here but I wouldn't mind taking a run at Kris Letang, this is a player that's been the second most productive defender of this era behind only Erik Karlsson. He's having a rough season, but this is a player that's been regarded as a number 1 defender for the past ~5 years. Having Chris Tanev on this team allows Letang to get easier deployment and can help anchor this teams power play for the next 5 years.
If you're able to "buy low" on him at the price of Alex Edler, Brandon Sutter and a young piece not named Horvat, Pettersson, Juolevi or Boeser I'd do it. A top 4 offensive minded RHD has been what this team has needed for as long as I can remember. He obviously has an extensive injury history and is on a pretty rich contract, but if they're able to move Sutter in this deal I wouldn't worry as much about Letangs cap hit.
Just spit balling here.