First priority: Finding players to play alonside Evgeni Malkin.
Plotnikov played next to Ovechkin in the 2015 World Championships and was a point away from his team's leader in scoring (2014/2015 season with Lokomotiv). Plus, since he's only 25, Pittsburgh can only give him an EL contract and can thus save alot of money buy only having to paying him in the $1M range.
Tikhonov, along with Plotnikov and Artemi Panarin (whom will reportedly sign with Chicago on July 1st), is in the top 3 for pending free agents from the KHL highly interested in making the move to the NHL.
Both Plotnikov and Tikhonov fit the bill to play with Malkin. If they do not succeed as many may hope, Pittsburgh still has Kunitz, Dupuis and Bennett that can prop themselves into those roles.
Second priority: What to do with Brandon Sutter?
I don't see a deal being made with Sutter involved any time soon. Any trade you make with him won't bring back a 3rd line center and if you were to bring in a winger while sending away Sutter, why? ... Wingers have already been taken care of with the signing of Plotnikov and Tikhonov coupled with the possible line demotions of Kunitz and Dupuis creating depth on the wings. Also how would you fill the hole you made be dealing Sutter away? Would you look to free agency? No way you get a player of Sutter's caliber at an affordable contract.
Finally, how to mend the loss of Ehrhoff and Martin?
Youth. Bring in Maatta to the top line and take advantage of Pouliot, Harrington and Dumoulin's EL Contracts. If that is too risky, bring in a guy like Cody Franson. Sure he may ask for a lot of money but he certainly plays in with the Penguins' system and bring great size to the defensive core. Additionally, his poor play in Nashville might reduce his cost!