Well, the good news is Portland can only offer him their biannual exception.
I think Fesenko needs to be re-signed. I value him higher than Kosta. Fesenko is the only true center on the roster (Koufos, Memo and Jefferson are all PF's playing the 5). He's big and physical and gives us something the others don't - namely, the ability to lay somebody out on the court. Additionally, Fes showed some promise in the playoffs. Koufos has only shown some offensive promise in the summer league.
Unless/until Memo is back at 100%, Fes can play 10-15 mins per game. And frankly, unless/until someone overpays him, why not sign a big guy who can knock heads.