Makes sense. Dmen are a highly valued commodity, and Tanev is a solid middle pairing guy signed to a good contract and given that he was a bit of a late bloomer, its fair IMO to say he's still in the middle of his prime.
Not a guy you want to give away cheaply. But at the same time, Vancouver isn't in a position where they aren't contending for 2-3 years or more at least. It might be worth it to trade Tanev for a great futures package instead.
But if they dont get something really great I think keeping him is a good play as well. Edler on the other hand. He needs to go.