I would trade him (Kovy) for a second or a conditional second, if the best offer is a third round is the best offer you get , keep him and sign him to a 1 year $ 2.75 million dollar contract.
As for Petry and Tartar, unless its a first round pick, sign them; they will be hard to be replace and can certainly contribute for the next 2-3 years.
There contract are the wild card when Domi, Gallagher and other will need contracts in a few years.
Habs do have some great kids in the pipeline like Caufield and Romanov but they may need one more year of seasoning.